MARSHALL ISLANDS. Majuro Atoll. A sea wall has been built along some of the coast of Majuro Atoll in a bid to prevent the capital being flooded by the Pacific Ocean, but it is impossible to defend more than a fraction of the islands. Majuro Atoll has more than 80km (50 miles) of coastline but is only 50 metres (164 feet) wide in places. Only major urban centres and installations like the power stations have sea defences. 2004.