The limit for ordinary recreational diving is approximately 40 meters. The world record for scuba diving is 318.25 meters, broken by a South African diving enthusiast named Nuno Gomez at the famous diving resort of Dahab in the Red Sea of Egypt.
With the help of special equipment (tools)
The secret submarine of the US army can dive to a depth of about 1,035 meters. The Japanese submarine Shinkai 6500 dived to a depth of approximately 6,492 meters.
To add to the absurdity, the current deepest drilling depth is 10,683 meters (2010), and the currently known deepest ocean depth is 10,916 meters (trough of the Marianas).