From the ArcaMax Publishing, Trivia Newsletter:
http://www.arcamax.com/news/trivia/s-362750-961847
The Blue Hole is located just off of the coast of Belize, near the Ambergris Caye. The Blue Hole began as a limestone cave in our last Ice Age. After ages of erosion the cave collapsed leaving the scenic beauty we see today. The Blue Hole is almost perfectly circular reaching 300m (1000ft) across and 120m (400ft) deep.
This news arrived on: 06/13/2008