The soil below about 4 feet depth in most climates is at a constant 50 degree temperature — almost benign in its impact on heating or cooling. (proudgreenhome.com)
For all the practical purposes the over 400 - foot depth makes the Blue Hole a bottomless pit. (ambergriscaye.com)
Here, in the 40 - to 60 - foot depth range, divers can fit through deep ravines with walls 20 to 30 feet high, and explore maze - like networks of tunnels, caverns and arches that wind through the ancient limestone underpinning of the reef. (caradonna.com)