Scientists who study the ocean floor are called marine geologists or oceanographers (specifically, physical oceanographers).

Here's why:

* Marine geologists focus on the geology of the ocean floor, including its composition, structure, and history. They study things like seafloor spreading, plate tectonics, and the formation of underwater mountains and canyons.

* Oceanographers study all aspects of the ocean, including its physical, chemical, biological, and geological properties. Physical oceanographers specifically focus on the physical processes of the ocean, including currents, waves, and tides, which all interact with the ocean floor.

So, while both terms are relevant, marine geologist is the most specific term for a scientist who focuses on the ocean floor.