- Sylvia Earle
- 381 metre(s)
- United Kingdom ()
The deepest untethered sea walk is 381 m (1,250 ft), achieved by Sylvia Earle (USA), on 19 September 1979.
Dr. Earle was strapped to the front of a small research submersible in a JIM diving suit. Once on the seafloor, Earle untethered herself from the vehicle and explored the seabed for over two hours.