Belize Barrier Reef

Belize's most famous site — a near-perfectly circular marine sinkhole in Lighthouse Reef Atoll, roughly 124m/410ft deep; recreational dives stay in the approximately 40m/130ft cavern-ledge zone among giant stalactites up to 12m long. A geology dive, not a wildlife dive: multiple sources describe fish life here as sparse, with only occasional, unreliable Caribbean reef shark sightings near the entrance — the real, reliable shark encounter on this day trip is the paired stop at Half Moon Caye Wall, not the Hole itself.

A wall drop-off at Lighthouse Reef Atoll, always paired with the Blue Hole on the same day-boat trip out of San Pedro, Caye Caulker, or Belize City. The atoll's reliable Caribbean reef shark site — also turtles, spotted eagle rays, groupers, and giant barrel sponges along the wall. A liveaboard can reach it too but is not required for this day-trip-accessible site.