This is an introduction to deep earth diving in Bonne Terre Mine in Missouri including dive trail #1. The St. Joseph Lead Mine at Bonne Terre commonly refereed to as Bonne Terre mine was started in the 1860's and operated until the 1960's. The temperature inside the mine is a cool 65 degrees fahrenheit all year. The water temperature ranges from 56 58 degrees all year with no thermocline. There are lots of mine artifacts to see and the crystal clear water provides well over a 100 feet of visibility. JacquesYves Cousteau once visited the mine and did some filming.