Related Clues:

• See 23-Down
• Ebb and neap, e.g.
• Neap and ebb
• Surges
• Potential sandcastle destroyers
• High and low, e.g.
• Surfer's concern
• Bay of Fundy attractions
• Ebb and others
• Sea motions
• Neap and spring
• Ocean motions
• Sailing concerns
• Ocean movements
• Holds, with 'over'