Harley was intrigued, and together with geographer Kristine DeLong of Louisiana State University, set out to discover the site's secrets.
The research team created a sonar map of the area and analyzed two samples Raines took from trees. DeLong is planning her own dive at the site later this year. Because of the forest depth, scuba divers can only stay below for about 40 minutes before coming up.
Carbon isotopes (atoms of the same element that have different molecular weights) revealed that the trees were about 52,000 years old.
The trees' growth rings could reveal secrets about the climate of the Gulf of Mexico thousands of years ago, during a period known as the Wisconsin Glacial period, when sea levels were much lower than they are today. (World's Weirdest Geological Formations)
In addition, because Bald Cypress trees can live a thousand years, and there are so many of them, the trees could contain thousands of years of climate history for the region, Harley said.
"These stumps are so big, they're upwards of two meters in diameter - the size of trucks," Harley told OurAmazingPlanet. "They probably contain thousands of growth rings."