Related Clues:

• Lagoon former
• Reef around a lagoon
• Island with a reef
• Coral island
• Ringlike formation
• It's often formed around a sinking tropical island
• Castaway's locale, maybe
• South Seas spot
• Key chain?
• One in a chain, often
• Ringlike island
• Bikini, among others
• It consists of a circular coral reef surrounding a lagoon
• Proving ground
• Isle with a lagoon