The concrete piers of a five-kilometre bridge turned into a reef, anemones, dead man's fingers and sponges, with lobsters…The concrete piers of a five-kilometre bridge turned into a reef, anemones, dead man's fingers and sponges, with lobsters, crabs, cuttlefish laying eggs in spring, and the highest biodiversity of any Dutch water. Not clear, but alive. The Oosterschelde was going to be dammed after the 1953 flood killed 1,836 people, and was instead given a storm-surge barrier that closes only in storms, keeping the estuary tidal and salt. That engineering compromise is why the marine life is here at all. Anchorage: The Oosterschelde behind the Delta Works barrier is protected water; Zierikzee and Colijnsplaat are the harbours. Hazards: Tidal streams that will take you away if you miss slack water, plus shipping in the channel. Dutch divers plan every dive here off the tide table. Meer