A pioneering study of life recorded in giant sinkholes that extend far below sea level has shown scientists the catastrophic impact that ancient communities had on their environments.
Divers dig deep for the hole truth about our ancestors Telegraph.co.uk - March 4, 2008

Expert divers and scientists recently carried out the first sophisticated excavation on a hole in the Bahamas, which provided a rare glimpse of life before humans arrived. The cave on Great Abaco Island, known as Sawmill Sink, contains a host of well-preserved fossils, many from species that are now extinct. These include the first entire skeletons found in the West Indies of a 2,500-year-old tortoise and an unusual crocodile that roamed the land, along with bones from a lizard, snakes, bats and 25 species of birds, not to mention abundant plant fossils. Diver Brian Kakuk, a consultant for the Bahamas National Museum, discovered the first Sawmill Sink fossil - the giant tortoise shell, which was in excellent condition.

But long before tourists arrived in the Bahamas, ancient humans had taken up residence on this archipelago off the coast of Florida. The subsequent disappearance of species from the fossil record offers stark evidence that the arrival of humans permanently changed - and eliminated - life on what had been isolated islands.CONTINUES...
https://www.telegraph.co.uk/earth/main.jhtml?
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The West End Of The Well
https://www.delange.org/MontezumaWell/MontWell.htm
Montezuma's Well is a sinkhole, a collapsed underground limestone cavern filled with water. For at least 2,000 years, the outflow from Montezuma Well (which, is a misnomer, having no connection at all with the 16th Century Aztec ruler) has been directed through a channel to fields where Hohokam and Sinagua farmers tended corn, beans, squash, cotton and other crops. The ancient irrigation channel now empties into Beaver Creek.

More than a million gallons of water a day flow continuously, providing a lush, oasis in the midst of a surrounding desert grassland. Montezuma's Well is about 368 feet across and 55 feet deep; it sits at an elevation of 3,618 feet.

The well is a unique ecosystem containing leeches, amphipods, water scorpions, and turtles that live in it's closed ecosystem. This remarkable habitat is perhaps due to the receiving and the discharging of large quantities of warm (76° F) water that enters from underground springs, keeping the well's environment very stable.

Due to it's high concentration of dissolved carbon dioxide, there is a lack of oxygen, which has precluded many aquatic animals from living in it's waters, especially fish.

From about 900 to 1400 A.D., it supported a community of over 200 Sinagua Indians, and about 1.1 million gallons of water a day still flow from it.

Built into Montezuma's Well's rock walls are several cliff dwellings typical of the Sinagua civilization, and other Sinagua stone structures dot the nearby lanscape.