Florida is pretty much a peninsula of limestone caverns. Shit drilling on the coast up near Awendaw which is about halfway to Myrtle Beach from Charleston. I can drill 400ft on Kiawah island without hitting any limestone. The Further north up the coast we go we start getting into the limestone at about 150ft, which makes for great drinking water well/irrigation well. But we were putting in a ground source heat pump. There is another fancy neighborhood otw to Mrytle Beach called DeBeadue and we drilled about 40 feet and all of sudden all our drill mud starts getting sucked into whatever cavern we were in, we tried fine bentonite mixed with water to plug it, tried using recycled insulation and this cavern we couldn't;t stop it up, we pumped 5000 gallons of bentonite /and the insulation mixture. We were still new to everything well drilling can throw at you, and now we would use well casing for each borehole. You learn and live. All I can say is all the people I manage went home safe, with all their eyes, ears, fingers, toes, and cannot include a brain, some of the helpers they have stuck me with are lacking on the brain part, I cannot help that they were born like that or how their parents brought them up.