Purpose-sunk wrecks and artificial reefs including Le Serpent, plus lobster, cuttlefish, sea bass and enormous numbers of…Purpose-sunk wrecks and artificial reefs including Le Serpent, plus lobster, cuttlefish, sea bass and enormous numbers of shrimp, all in still water with no tide to plan around. Winter night dives here are a Dutch tradition. The Grevelingen was cut off from the sea by the Delta Works in 1971 and turned from an estuary into the largest saltwater lake in Europe. A sluice was added later to let seawater in again, because the lake was suffocating without exchange. Anchorage: A tideless saltwater lake with marinas, sheltered water and no current, the easiest cruising water in the Netherlands. Hazards: Deep water anoxia in parts of the lake in late summer; local divers avoid the affected basins. Plus