Possible Clues:

• Water by Gilligan's Island
• A salt-water lake enclosed by reef
• Atoll lake
• Turn in Louisiana on lake
• Stretch of water inside coral reef or sandbank
• Water protected by a coral reef
• Water surrounded by sand dunes
• Make slow progress without swimsuit in the pool
• Might the French go on to be calm there?
• Stretch of water within an atoll