Gulf of Finland

Everything runs off a boat. The wrecks lie too far out for shore entries, so a diving day means an early start from a harbour on Finland's south coast, a run out through the archipelago, and a shot line dropped onto a mark the skipper already holds on GPS. Two dives is a long day once cold and depth are accounted for. Permissions come first rather than last: access to the protected sites is arranged with the operator weeks ahead, not settled on the morning of the trip.

The bottom over much of the gulf is soft mud and clay with little relief, so wrecks are found on sonar rather than by swimming a contour, and each one holds whatever structure and life there is for a long way around. Sites fall into three rough groups: intact sailing hulls standing on the deeper ground, where the interest is rig and fittings; broken steel and steam losses shallower in; and the rock shelves and boulder slopes along the archipelago edge, which clubs use for skills work and check dives.

Light is what divers underestimate. Baltic water carries a brown humic tint from river run-off, and late-summer algal blooms can thicken the upper few metres further, so below the thermocline a torch stops being something you point into a hold and becomes the only way to see the ship at all. Hulls arrive out of the dark a few metres at a time. Winter is a separate exercise: from February into April crews cut holes in sheltered bays and dive on a tended line with surface cover, working shallow and short. November and December fall between the two, boats laid up and no ice yet.

The area suits divers who came for the ships rather than the animals, and who can accept losing days to weather, ice and paperwork. Most of the scene runs through Finnish clubs and a small number of specialist operators rather than walk-in shops, so trips are put together well in advance, usually as a group, and often around one particular target. Anyone after easy, high-volume holiday diving should look elsewhere; anyone with an interest in maritime history will think the effort a fair trade.