"Natural sinkholes" refers to depressions or holes that naturally develop in the ground. They are caused by factors like erosion or the collapse of underground rocks, creating a hole in the earth's surface. Full definition
Your kids will love the multicolored fishes living in the ocean or inlets through their snorkeling mask, the legendary blue shades of the Caribbean Sea, the mysterious lush jungle, home for endemic and beautiful species, the sacred cenotes or natural sinkholes with impressive rock formations. (royalreservations.com)
Hundreds (if not thousands) of «cenotes», natural sinkholes filled with crystal blue fresh water. (foodfuntravel.com)
These are natural sinkholes in limestone bedrock, some are underground, some are open - air and some are a combination of both. (cantravelwilltravel.com)