What is a scientist that works in the water called?

Answer 1

A number of different scientists work in the water, at least part of the time. The marine biologist does, and the underwater archaeologist does, and they are probably the main ones. So does the oceanographer and the hydrologist, but not nearly as much. There probably isn't a science where the work is done exclusively under water, but there are many that require the scientist to "get wet" while working. These and a few other scientists work in water at least part of the time while continuing their observations and investigations.

Answer 2

An oceanographer studies the physical, chemical, and biological aspects of the ocean and other bodies of water. Their work involves understanding ocean currents, marine life, water quality, and other related phenomena.