The scientist who studies rocks and ocean basins is called a Marine Geologist.

Here's why:

* Geology: The study of the Earth's physical structure, history, and processes.

* Marine: Relating to the sea or ocean.

Marine geologists specialize in the geology of the ocean floor, including:

* Rock formations: Analyzing the types of rocks found on the ocean floor, their age, and how they were formed.

* Ocean basin structure: Studying the topography of the ocean floor, including trenches, ridges, and plateaus.

* Plate tectonics: Investigating how the movement of tectonic plates impacts the ocean floor and creates features like volcanoes and earthquakes.

* Seafloor sediments: Analyzing sediments found on the ocean floor to understand past climate, ocean currents, and biological activity.

So, a Marine Geologist is the expert on the rocky and fascinating world beneath the waves!