I'll like to suggest "demersal-dive". The word demersal is bit too technical in terms of Oceanography (demersal zone) and Marine biology (demersal).
Definition of demersal in Merriam-Webster is given as follows:
living near, deposited on, or sinking to the bottom of the sea.
Definition of demersal in Oxford is given as follows:
(chiefly of fish) living close to the floor of the sea or a lake.
Origin: Late 19th century: from Latin demersus (past participle of demergere ‘submerge, sink’, from de- ‘down’ + mergere ‘plunge’) + -al.
The Demersal zone in the sea/ocean.
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of the larger profundal zone. wiki
There is a rare usage of the phrase "Demersal Divers" as in the book: Writes of Passage by Phil Wallace Payne.
Oxford dictionary states that "demersal" is often contrasted with pelagic. Pelagic (chiefly of fish or of a bird) inhabiting the upper layers of the open sea.