“Blue Holes,” as they are often called due to the small circle of water they form in the inland soil (and their similarities to the more well-known offshore variety), sometimes form the entrance to a vast network of underground caverns.
The caverns are completely submerged and contain zero or near-zero percent oxygen – and that’s just the first of their remarkable traits. Scientists looking to gain an understanding of what life might be like on planets other than Earth have very few resources to turn to.
The planet they live on happens to be nearly 100% Earth, and the alternate environments they have some access to (the moon, Mars) happen to, thus far, have zero life forms.
So they turn to some of Earth’s least hospitable environments to see what’s going on there. Research takes them from the cracked desert floor of the Mojave to the North Pole and the sub-freezing water beneath it – anyplace, really, where nothing might turn into something.
But the caves in the Bahamas have something those other places don’t: diversity.
Zero light and an underwater environment have created some interesting life forms in other places, but the unique combination of reduced gravitational effects and a saltwater-rich environment largely shielded from external forces have created a fascinating incubator for the growth of microorganisms.
And perhaps more importantly, a lack of others – the bacteria that usually cause trouble for terrestrial environments have a hard time growing here, and if they do, it’s in a unique way that results in a high volume of deadly hydrogen sulfide.