The 1,043-foot-wide hole came to be after an above-ground cave collapsed some 15,000 years ago. Today, it's a UNESCO World Heritage site and a great spot for beginner divers.
Blue Holes is a large, deep cavern beloved by adventurous divers. There are four holes in the reef that enter the cavern, which is home to wire corals, sea fans and leopard sharks.
Vines drape from the ledge of the 200-foot-wide opening above, and a staircase leads visitors down to the edge of the water of the famously beautiful Ik Kil cenote.
Known as the 'door to Hell,' this crater isn't a natural sinkhole. It was lit on fire after drilling and collapse lead to methane gas leaking. It's been burning ever since.
This is considered one of the most beautiful sinkholes on the planet, and it serves as a swimming hole for local residents and tourists who come to see its azure waters.
This is the world's second deepest known saltwater sinkhole, plunging 663 feet into the bay off Long Island. It's also the site of many freediving stunts.
Montezuma Well was formed by the collapse of a limestone cave. Today, more than a million gallons of water flow through the sinkhole each day.
Known as an 'underwater cathedral,' this sinkhole is 394 feet deep and is lined by gorgeous coral. It's infamous for being dangerously deep and disorienting.
Appearing as a perfect, secluded lagoon oasis in the jungle, this blue hole is reachable via a 2-hour paddle up a tidal river during an incoming high tide.