Here’s the wave at Dungeons in action, seen from the top of Chapmans Peak drive. You can see the mess of white water just to the left of the Sentinel; this is where Dungeons is.
The wave comes to life under particular conditions that usually arise during the Cape Town winter: a long period, massive swell from the correct direction, along with favourable winds. It’s a very popular big wave surfing spot that mostly requires support from a jet ski, but not for the faint hearted. The wave breaks just out to sea from Duiker Island, and the white water washes over the island after the wave breaks. I don’t know where the seals go!