Related Clues:

• Helmsman's challenge
• Atoll feature
• ___ shark
• Erosion by-product
• Shallow sea area
• Coral buildup
• Atoll, essentially
• Coral construct
• Atoll's makeup
• Ship wrecker
• Shipwreck locale
• Diver's haunt
• Atoll, for one
• Coral Sea hazard
• Coral line