Tides – Page 4 – Learn to Dive Today Blog

Bookshelf: The Sea Around Us

The Sea Around Us – Rachel Carson

Rachel Carson was a marine biologist, conservationist and writer whose life and work should serve as an inspiration to any independently minded schoolgirl considering a career in the sciences. I wish I had heard of her when I was younger – she carved out a career for herself quite outside of the expectations that society held for women in the first half of the 20th century.

She wrote several books, of which the fourth, Silent Spring (concerned with the increasing use of pesticides and their effects on humans and the environment), is probably her best known. Her second book, The Sea Around Us, published in 1951, was the one that initially propelled her into the public eye.

The Sea Around Us is a natural history of the sea, based upon the oceanographic and scientific knowledge of the workings of the world’s oceans that was available at the time of writing. I read an edition of this book that Carson updated in 1961 with knew scientific developments of the last ten years, and there are other editions available with supplementary chapters that bring the science and oceanography completely up to date. The required updates aren’t sufficiently vast to render the book useless or even annoyingly out of date, and indeed, once you’ve read some of Carson’s prose it becomes clear that the majesty and poetry of the sea is as much the subject matter here as the science.

The first chapter of the book, describing the origins of the oceans, reads like a creation myth – one that has some science behind it, however! It just begs to be read by a sonorous, James Earl Jones-type voice, and captures perfectly what it is about the ocean that fascinates us. Here is the first paragraph:

Beginnings are apt to be shadowy, and so it is with that great mother of life, the sea. Many people have debated how and when the earth got its ocean, and it is not surprising that their explanations do not always agree. For the plain and inescapable truth is that no one was there to see, and in the absence of eyewitness accounts there is bound to be a certain amount of disagreement. So if I tell here the story of how the young planet Earth acquired an ocean, it must be a story pieced together from many sources and containing whole chapters the details of which we can only imagine. The story is founded on the testimony of the earth’s most ancient rocks, which were young when the earth was young; on other evidence written on the face of the earth’s satellite, the moon; and on hints contained in the history of the sun and the whole universe of star-filled space. For although no man was there to witness this cosmic birth, the stars and moon and the rocks were there, and, indeed, had much to do with the fact that there is an ocean.

The Sea Around Us, Chapter 1, “The Gray Beginnings”

Carson’s focus is more on oceanographic information than on marine biology, although she does devote several chapters to the life found within the oceans. It was lovely to read about the palolo worms of Samoa, after seeing the BBC South Pacific episode that deals with them. Carson also writes with reverence about the sargassum weed that is captured in a massive gyre in the Atlantic ocean, and describes the hosts of small creatures that make their homes in and beneath the weed.

My favourite sections were the chapter on the birth of an island through volcanic processes, and her explanation of tides. In my reading prior to our Malta holiday last year, I tried desperately to figure out why in Malta there is almost no tidal movement, and in other places (Jersey in the Channel Islands and the Bay of Fundy spring to mind) the tidal range is so vast. Moreover, not all parts of the world experience two high tides per day – some regions, such as the Gulf of Mexico, only experience one high and low tide daily. How could this possibly be the case? Carson explains tidal science as simply as it can be done, and in the process gave me just enough information to satisfy my curiosity but not enough to give me a headache. Tides are determined by the moon and to a lesser extent the sun – every school pupil knows this – but the shape of the coastline, ocean basins and nearby land masses also go a long way to determining tidal range and frequency. If you’re interested in this subject you could do some preliminary reading here, here and here.

This is one of those books that will delight ocean-minded people, but that will also persuade those who are less fascinated with the sea that it is something wonderful and worth thinking about. Carson’s conservationist urgency is less to the forefront of this book than, say, Carl Safina‘s is in his books, but it is there nonetheless. I found it deeply disturbing that sixty years ago it was already painfully obvious that fishing pressure at its then-current levels (nowhere near as technologically advanced as it is today) was removing marine life from the ocean faster than natural processes of birth and growth could replace it.

The Sea Around Us is a beautiful and important book that will occupy your thoughts long after you finish reading it. You can buy the book here if you are in South Africa, and here if you’re not. For Kindle, try here or here.

Dive tourism in Malta (and some hints for South Africa)

Last year August, Tony and I spent a blissful week in Malta, diving ourselves silly in the mornings and napping in the heat of the afternoon. In the evenings, we ate ice cream and participated in the time-honoured Italian tradition of the passegiata.

The nation of Malta comprises three small islands located just south of Italy, in the Mediterranean Sea. The water is warm, there is almost no sand around the islands (most of the beaches are man-made), the limestone structure of the islands gives rise to caves, swim throughs and gullies to explore, and there is negligible tidal activity. The climate in summer is almost boringly warm and stable and with the exception of some violent winter storms, the ocean surrounding Malta is welcoming all year through. These factors combine to make it an extremely attractive location for scuba diving.

Malta’s natural charms, however, are greatly enhanced by her government’s approach to dive tourism. Recognising that visiting divers bring considerable income to all sectors of the Maltese economy (divers eat, need somewhere to sleep, and can’t spend all day diving!), the government has over the years scuttled a number of ships (ten or more at last count) as attractions for divers. These include the Um El Faroud, the Imperial Eagle, the P29, and the Rozi – all of which we dived. There are also a number of World War II wrecks (submarines!) around the islands, many at depths suitable for technical diving only.

Diving in Malta is well regulated. The Professional Diving Schools Association is a voluntary organisation representing over 30 dive centres in Malta, and encourages its members to adhere to high standards of safety and care. Divers visiting Malta are required to complete medical questionnaires before being allowed to dive, and are required to adhere to certain other regulations governing divers and their safety.

We very much enjoyed the wrecks in Malta, and found a special charm in even the newer ones that were scuttled in the last five years. The P29, for example, was almost clear of marine invertebrate growth, and all the wrecks were still discernible as the beautiful ships they once were. Surrounding them we found scores of fish – damselfish, barracuda, and the odd tuna.

There are several purposely-scuttled wrecks available around Cape Town, but there’s been no additional activity on this front for years. Only the Aster – the newest wreck, scuttled close to 20 years ago – still looks much like a ship. The Smitswinkel Bay wrecks – the Good Hope, Transvaal, Orotava, Princess Elizabeth and Rockeater, were scuttled over 30 years ago and have been pounded by the rough winter seas of the Cape. They are recognisable as ships, but penetrating any of them is a mug’s game and often during dives on these wrecks one can hear them creaking and groaning in the surge. The SAS Pietermaritzburg is in an even more exposed position off Miller’s Point, and is yet more beaten up despite being more recent than the Smitswinkel Bay wrecks.

Before I get shot down in flames for trying to compare Maltese and South African wrecks (age differences aside), let me qualify my statements. I recognise that there are significant differences between the Mediterranean Sea around Malta and the two oceans surrounding the South African coast – here are two:

the quantity of biomass that is supported off the Cape coast is far greater than that supported by the almost sterile (I exaggerate) waters of the Med – invertebrates quickly cover available surfaces and blur the outlines; and
the tides and currents around our coast are fierce and strong, and in a short time weaken any structure placed underwater.

What isn’t different, however, is how valuable scuba diving tourists are to the countries’ economies. Divers who have the means to travel and scuba dive also have the means to enjoy other activities in their destination countries. Diving is often a hobby of those who generally enjoy the outdoors, and a country like South Africa (as opposed to, say, Dubai) has a wealth of experiences in nature to offer such tourists.

Very little grows in Malta, and the islands are hilly but no one would travel there for that reason alone. Compared to Malta, South Africa is ridiculously blessed with spectacular landscapes and wildlife both above and below the ocean. South African divers also know the tropical wonders of Sodwana, the chilly but exhilarating shark, wreck and reef diving available in the Cape, and the incredible ecosystems in between. This is all in addition to our mountains, deserts, fynbos, bush, and coastal scenery. Why isn’t more made of our underwater heritage?

It would be wonderful to see the South African government and South African National Parks being receptive to more properly cleaned wrecks being scuttled around our coast in locations suitable for recreational diving. More Marine Protected Areas, properly policed, would be good. It would also be great to see local dive centres striving to offer meaningful, repeatable diving experiences to tourists, instead of seeing them as once-off cash cows who can be taken out for a dive in appalling conditions because they aren’t coming back anyway. It would also induce much joy if airlines of all sizes in South Africa recognised (as Air Malta does) that scuba diving is a sport, like (ahem – sorry divers) golf, and gave an extra luggage allowance for scuba diving equipment.

I don’t think enough is done to encourage tourists to visit this country in order to dive, or with diving as one of their primary activities. It would benefit everyone – not just dive centres and dive charters – if more could be made of this opportunity. The example of Malta is a good one.

Just blue water in Malta

A short, slightly random video clip I took on the ferry that runs from Cirkewwa in Malta to Gozo. We’d taken the ferry to go and dive the Blue Hole and Inland Sea on Gozo, and on the way back we stood by the rail admiring the magnificent blue of the water beneath us. Malta has no tidal activity and almost no sand close to shore, so the water is ridiculously clear and blue.

[youtube=http://www.youtube.com/watch?v=y4Il2jPCecI&w=540]

If you have your speakers on, you’ll hear us discussing the next day’s diving on the Um El Faroud.

Bookshelf: Atlas of Oceans

Atlas of Oceans – John Farndon

I confess that I was not totally enamoured of this book when I started reading it. It seemed overly simplistic, but by the time I finished it I realised that its author had neatly summarised both the wonder and variety of the world’s oceans, and the threats facing them from human activity.

Boasting a foreword by Carl Safina, whose most well-known book is Song for the Blue Ocean, the book is written by John Farndon, a prolific children’s author, and published by Yale University Press. Farndon is British, as is evidenced by his assertion, during a discussion of the warming effect that the Gulf Stream current has on the north Atlantic ocean, that Great Britain has a very pleasant climate. No one else – except perhaps an Inuit – would make such a claim.

Farndon’s credentials as a science writer for children make this volume a pleasure to read – he deals with wide ranging and fairly complex topics, but in a completely understandable way. The book is well illustrated with photographs (some – such as ones of a row of narwhal and a calving ice shelf, of dubious quality), diagrams and maps. The sections each cover two facing pages, so it’s quick to dip into and finish reading a section before bed (for example)!

Special sections focusing on particular habitats (such as coral reefs or the ice), wildlife (I was particularly charmed by the highly endangered vaquita) and issues (mainly related to conservation) are spread throughout the book. Farndon lays the groundwork for a basic understanding of our oceans by covering concepts such as ocean tides, currents and physical oceanography, and then moves on to specific sections on each of the world’s oceans. He also writes about the major seas, such as the ones in Europe and the South China Sea.

This isn’t a long or complex book – it’s under 250 pages long – but comes with a glossary, a list of endangered species (including their status of endangerment and scientific name), suggestions for further reading, and contact details for a long list of ocean conservation organisations. It’s the kind of book that I will dip into frequently – there are some useful photographs (one of the marks left on the seabed by bottom trawling fishing boats springs to mind) and maps (I liked the one showing the whole 2% of the world’s oceans that are in marine protected areas – MPAs) and excellent coverage of the overfishing problem facing us today. Also dealt with are oil spills, whaling, global warming, coral reef and ice shelf destruction due to warming of the oceans, dead zones that result from fertiliser runoff into the sea, and anything else you can think of that impacts the health of our oceans.

An edited extract from the book can be found here, along with a magnificent photo of a basking shark. I recommend it, and it’s suitable and accessible for anyone from a precocious ten year old and up. It’s the sort of book you could give to someone who doesn’t know much about or care particularly for ocean matters, and it would bring them right up to date (and probably make them care).

You can buy the book here if you are in South Africa, and here if you’re not.

Friday poem: A Beginner’s Guide to the Ocean

A Beginner’s Guide to the Ocean – Ogden Nash

Let us now consider the ocean.
It is always in motion.
It is generally understood to be the source of much of our rain,
And ten thousand fleets are said to have swept over it in vain.
When the poet requested it to break break break on its cold gray rocks it obligingly broke broke broke.
Which as the poet was Alfred Lord Tennyson didn’t surprise him at all but if it had been me I would probably have had a stroke.
Some people call it the Atlantic and some the Pacific or the Antarctic or the Indian or the Mediterranean Sea,
But I always say what difference does it make, some old geographer mumbling a few words of it, it will always be just the Ocean to me.
There is an immortal dignity about something like the Atlantic,
Which seems to drive unimmortal undignified human beings frustratedly frantic.
Just give them one foot on the beach and people who were perfectly normal formerly, or whilom,
Why, they are subject to whoops and capers that would get them blackballed from an asylum;
Yet be they never so rampant and hollerant,
The ocean is tolerant,
Except a couple of times a day it gives up in disgust and goes off by itself and hides,
And that, my dears, accounts for the tides.

Handy hints: Kelp diving

Contrary to popular belief, nothing bad will happen to you if you get caught up in a bed or forest of kelp. It may be inconvenient, and slow you down briefly, and you may experience emotion of extreme resentment and sheepishness like those that Kate is clearly experiencing in the photo above (taken at A Frame), but you won’t drown or be trapped forever amid the slippery brown strands.

If you really have a problem with kelp, I suggest that you only dive areas with lots of kelp at high tide. You won’t have as much of a problem with a surface swim through dense kelp forests when the tide is fully covering the kelp stipes, but in a situation when the tide is low (as above), a surface swim becomes a slow and awkward proposition.

Kelp blades (the leaves) are flat and very smooth, and while you may feel that they are wrapping around you, they’re really just sliding over your wetsuit. Move slowly, don’t panic, and use your hands to keep your face clear. Lots of awesome critters live in the kelp – don’t be a hater!

Bookshelf: The Devil’s Teeth

The Devil’s Teeth – Susan Casey

It’s rare for me to take as complete and instant a dislike to the author of a book as I did in this case (Elizabeth Gilbert of Eat, Pray, Love fame is the only other example I can summon to mind). Susan Casey is a magazine journalist who counts employment at O Magazine among her career highlights – but this isn’t the reason I took a dislike to her… Keep reading.

I suppose I am looking for a book about sharks that doesn’t exist. Briefly, here and there, this was that book. Casey describes the Farallon Islands, remote and hostile rocky outcrops some 50 kilometres from San Fransisco. Like our Seal Island in False Bay, the Farallones are home to many marine mammals and a large number of great white sharks (some of epic proportions).

Casey describes the birth of her obsession with the islands (she watched a TV show) and the sharks that call them home, as well as their history as a source of seabird eggs (they are an important nesting site). She recounts various visits she took to the islands, culminating in a long stay in 2003.

Casey’s ruminations about how dirty her hair was, what she packed for the trip to the islands, how clueless she is about boats, and how obsessed she – personally – is with white sharks are uninteresting, but her descriptions of the sharks themselves, the research being conducted with them, and the individuals – incredible to a man – conducting that research, are at times rewarding. A keen objectifier of men (like Elizabeth Gilbert, actually), Casey spends a lot of time describing the rugged good looks and well-defined musculature of the various researchers and scientists she encounters – really classy, and respectful of them as scientists and individuals rather than as eye candy. HA! I did wonder more than once if a continuation of this line of thought could explain how she managed to secure a stay on the islands despite them being officially closed to visitors…

Fascinating nuggets are, however, gleaned here and there. The predations at the Farallones generally do not involve the breaching we see at Seal Island, perhaps because the sluggish elephant seals living there do not require the same degree of exertion as frisky Cape fur seal pups do. The attacks mostly take place at high tide. The observations of Ron Elliott, a commercial diver who harvested sea urchins at the islands (the only one who dared) are fascinating – he’d see sharks on almost every dive he did, and hid from them under the rocks where necessary. Upon climing into the water, he’d duck straight under his little boat so as to avoid presenting an interesting silhouette from below.

On two occasions orcas killed a white shark at the island (in one case by holding the shark upside down until it drowned); after both predations, the other great whites vanished – just disappeared en masse. This is intriguing. Many marine mammals pass by – the islands are a popular whale watching location and up to 60 blue whales have been sighted at once. One of the researchers even became the first (and I think only) person to observe humpback whales copulating there. Apparently it takes two… Plus an assistant!

Something else I discovered here that I didn’t know is that the Monterey Bay Aquarium in California, one of the foremost aquaria in the world, has had great white sharks on exhibit on several separate occasions, starting in 2004. They don’t keep the sharks indefinitely – they grow fast – but they’ve managed to keep five sharks mostly happy and healthy, before realeasing them (tagged) back into the wild. The reasons for release varied from increased size, increased aggression, to refusal to feed.

Ultimately, this book is an account of a tragedy caused by its author, who seems unaware of the extent of the damage she wrought, and hence unrepentant. She forced herself – there’s no other word – into a delicate web comprising the predators, prey, and the scientists who observed their interactions, and then tore down part of the web by her very presence. Because of her stay on the islands, Peter Pyle, the researcher in charge of the Shark Project on the Farralones, lost his job. Thanking him profusely in the acknowledgements doesn’t really cut it, especially after quoting Pyle elsewhere in her book as saying that he loved the Farallones, and being on the islands, “more than life.”

Aside from shutting down an entire shark research project singlehandedly and causing a ten year veteran of the project to lose his job, Casey also misplaces a borrowed sailboat and breaks the law repeatedly and with gusto. If I’d made such an utter fool of myself, I wouldn’t have written a book about it, but she glosses over her responsibility so thoroughly that I suppose some readers may fail to ascribe to her the blame she deserves.

Buy the book here if you’re South African, otherwise here. Actually, don’t buy it – this woman doesn’t deserve any support at all.

Looking for seahorses in Knysna

Tony is obsessed – and I mean obsessed – with seahorses, and by all accounts has been hunting for them everywhere he’s ever dived. For this reason he was very keen to dive in Knysna, home of the Knysna seahorse, and to see if we could find some.

We go houseboating in Knysna every year (so far), and we’re able to dock the houseboat on Thesen Island at the jetty there. The first time we went, Tony’s friend Cameron showed us where to dive, and accompanied us in the water while his girlfriend Claire paddled her kayak around on the surface.

The magnificent Knysna Lagoon opens to the sea through a very narrow opening called the Heads. Because it’s so narrow, the tidal pull into and out of the lagoon is incredibly strong, and it’s not wise to dive while the tide is going in or out. The dive sites inside the Heads (and there are several, including a wreck called the Paquita which I’m dying to visit) should only be dived around the turn of the tide, from half an hour before to half an hour after, unless you have a hectic drift dive in mind (and some people do!).

The first time we dived the Sanparks Quay on Thesen Island was in August 2009, and we dived at high tide one afternoon. It’s a bit of a walk from the houseboats jetty to the Sanparks Quay, especially wearing full kit, but at high tide the entrance is reasonably easy. You just stride down some steps next to the quay and into the water. It’s a so-called junkyard dive, with lots of tyres, bottles and other bits of rubbish, but also very beautiful to see how the sea life has colonised the junk. At high tide the water is deep, clean, and still. The fishermen on the quay were profoundly amused by our antics, and one has to watch out for their lines and hooks while diving this site.

The seahorses are really hard to spot – many of them are brown (we did find a bright yellow one), smallish, and well-camoflaged among the debris. They wrap their little tails around things and sway in the current. We saw three or four, and Tony was so excited when we spotted the first one that I could hear him shouting through his regulator.

Dive date: 18 August 2009

Air temperature: 22 degrees

Water temperature: 15 degrees

Maximum depth: 5 metres

Visibility: 15 metres

Dive duration: 19 minutes

The second time Tony and I dived the Sanparks Quay was at low tide (high tides were at night while we were there) in June this year. We were alone, and it wasn’t as easy as the previous time. The bottom of the steps ended before the waterline, so we had to leap off instead of just walk into the water. The visibility was less than a metre – like swimming in ProNutro – so I held onto Tony’s arm for dear life for most of the dive because if he moved too far I lost him. The tide going out stirs up a lot of silt and brings dirty water from higher in the lagoon, which makes it very hard to see anything.

Despite the conditions, we did spot one tiny little sea horse, which made it worthwhile. There was also a crowned and an orange-clubbed nudibranch nudibranch, but we didn’t stay long because the conditions were so poor. We swam under the pier a little, which we didn’t do the first time. We learned why it’s a good idea to dive at HIGH tide next time!

Dive date: 16 June 2010

Air temperature: 20 degrees

Water temperature: 12 degrees

Maximum depth: 4.9 metres

Visibility: 0.5 metres

Dive duration: 35 minutes

If you don’t spot any seahorses, or don’t fancy a dive, you can visit the Sanparks office at the far end of the quay (closest to the Heads). They have a beautiful tank FULL of seahorses, who are extremely obliging photographic subjects.

Knysna seahorse in the Sanparks Building