The Tunnel is an unusual adventure involving two intrepid cave divers in the underwater caves of Central Florida. Carth and Louis are on a run-of-the-mill cave dive when something goes horribly wrong. A mysterious solo diver appears and saves Louis' life. The rescuer, Jim, and Carth become fast friends, but soon find themselves in an astonishing predicament, when they discover a new tunnel. With great effort they dig their way into the tunnel and into the unknown. Almost at the point where they should turn back, they see light from a sinkhole above, one that doesn't exist on any map. Do they stop and head back or do they risk their lives and ascend into the adventure of a lifetime?