Berlengas & Peniche

Every dive starts in Peniche harbour. There is no shore option out on the islands, so the day is a boat day: load in the morning, cross to the archipelago, dive, take the surface interval in the lee of the rocks, then dive again before heading back. The call is made the night before on the forecast and it goes against you often, since the north-westerly that gets up along this coast puts swell straight onto the crossing. Boats work the summer months and sit in port through the winter half of the year.

Granite behaves nothing like limestone or lava. The rock is jointed into blocks rather than dissolved into passages, so the swim-throughs are gaps between stacked slabs, the faces run near-vertical and split into fissures, and anything the swell reaches is scoured smooth. There is little loose sediment to stir up, which means clarity is set by plankton and swell rather than by fin technique, and it recovers quickly once the sea drops. Torches are standard rather than optional, since the tunnels stay dark at midday and a light does as much for finding the line through as for seeing colour.

Conditions sort the divers. Surge pushes through the tunnels, the outer rocks pick up current, and the water is cold enough that drysuits are common even at the height of summer. The archipelago is a protected reserve, so fishing is limited and the fish life shows it, and between June and September there is a real chance of the flat days that make the caves worth photographing. It suits experienced cold-water divers and macro shooters; anyone counting on a fixed number of dives should hold spare plans for the mainland coast.