Castle Rock is a boat-access pinnacle dive off Amorgos with a fish-rich passage, clear blue-water terrain, and antique pottery on the bottom. The site is known for dense fish activity and nearby fishing gear that demands careful buoyancy, so a skipper-led briefing and steady route choice matter more than a simple shoreline entry. It suits divers who want a short, memorable open-water outing with strong Aegean character rather than a flat reef swim.