Arraial do Cabo

Boats are small and fast and leave from Praia dos Anjos, the harbour beach beside the town centre, so crossings run in minutes rather than half-hours. A standard trip is two tanks with the surface interval anchored in a cove, and the skipper usually settles which sites to dive on the morning itself rather than a week ahead. Operators are clustered within a few streets of each other, which makes booking at short notice easy and makes a windy day easy to lose with nothing to do but wait it out.

The peninsula splits the diving in two, and which side you are on matters more than the site name. On the sheltered side the profiles are shallow, the ground is sand and low rock, and the water is calmer and warmer; a couple of those beaches also take shore entries, mostly for training. On the ocean-facing flanks the bottom falls away faster, surge pushes between the boulders and the fish concentrate in the moving water. Operators often do one of each so a closed-out outer site does not waste the trip.

When the cold water is in, the dive changes shape. You leave the warm surface layer, cross a hard thermocline partway down and finish the descent in cold, plankton-heavy water where visibility collapses and the rock is stacked with fish. It is neither a comfortable dive nor a pretty one by tropical standards, but those are the days divers come back for. The same northeast winds that set the upwelling going are the ones that keep the boats on the beach.

That swing is what to plan around. Arraial rewards divers who can stay flexible, who bring thermal protection they may not end up needing, and who care more about fish behaviour and rock structure than about warm water and coral. It works badly as a single fixed dive day booked from a distance and well as a long weekend with slack in it, which is how most people coming out from Rio treat it. Divers set on warmth and long sightlines are better served further north up the Brazilian coast.