The formations of Cenote Zapote, also known as "Hell's Bells" are world famous and extraordinarily rare. As the picture indicates, the speleothems found in this cenote are bell-shaped, as opposed to the spike-, pillar-, or curtain-shaped formations found in most shaped. As a result, they're strictly protected, both by Pluto Dive as conservationists and the folks that control access. While we encourage you to make the dive (it is, after all, a once-in-a-lifetime opportunity), we require you to have expert-level buoyancy, minimum of 50 logged dives and Advanced Open Water certification. Access is controlled by a special permit, and we will not submit for that permit if we do not believe you to be qualified.  Please check with us before booking this dive.