Big Blue Hole in Belize: Or, the Great Blue Hole

"The great Blue Hole in Belize"
Travel, The Los Angeles Times (undated)

"The 'great' Blue Hole on Lighthouse Reef Atoll is a popular diving spot off the coast of Belize. Visible in a flyover, the hole is about 1,000 feet in diameter and 412 feet deep. The late Jacques Cousteau and a filming crew explored the underwater cave whose roof collapsed about 10,000 years ago...."

Lots of cool photos.