Premuda

Diving here is boat diving and little else. Premuda is thinly populated and carries no resort scene, so divers come out with a centre from the mainland or a neighbouring island, dive two sites in a morning and spend the surface interval anchored in a bay rather than back on land. The sites sit close together along the island's flanks, so running times are short and the day is unhurried, with the weather forecast doing most of the planning.

The Cathedral rewards divers who move slowly. It is less a single cave than a linked set of vertical chimneys and chambers cut into the limestone, running from about 10 m down past 40, and the appeal is the light: beams drop through fissures in the roof and swing as the sun moves, so the same passage reads differently early in the day and at midday. Torch handling and buoyancy matter as much as depth, and centres run it as a cavern dive, with Advanced and cavern training expected.

Away from the cave the diving is classic northern Adriatic rock: limestone falling away in steps and overhangs, sponges and gorgonians on the deeper, colder faces, and cracks worth searching with a torch. Cape Lopata, a headland wall dropping from about 15 m to 40 m, is the natural pairing with the cave and suits divers who like to work one wall properly rather than cover ground. Currents are generally mild, but the exposed outer side picks up when the wind turns.

It is an island for confident intermediate divers rather than newcomers. The best of the cave lies deep enough to eat gas quickly, and the water below the thermocline stays cool well into summer, so an extra layer is normal even in August. Technically trained divers come for one thing only: the battleship Szent István, torpedoed in 1918 and lying inverted at 66 m some twelve kilometres offshore, which is trimix diving arranged through a centre equipped for it. Build in spare days, because the bura can shut the crossing at a few hours' notice.