Developments in sonar, both depth-profiling and side-scan, and in sea-bed mapping generally for the overall topography, and in remotely-controlled submersibles for studying details.
The adjective "underwater" isn't needed, BTW! :-)
The mid-ocean ridge are mountains that were formed underwater.
mid-ocean ridge
Mid- ocean ridge is the part of the continuous underwater mountain range that circles earth.
ocean ridge
Mid-ocean ridge. An example, is the mid-atlantic ridge.
A mid-ocean ridge is not an underwater volcano. It is a long mountain range on the ocean floor formed by plate tectonics. Underwater volcanoes, also known as seamounts, are mountains that form from volcanic activity on the ocean floor.
Mid ocean ridge
An ocean ridge is and underwater mountain range which is formed in the same way as an above water mountain range, by plate tectonics.
Underwater mountian ranges/ underwater volcanoes
Mid- ocean ridge is the part of the continuous underwater mountain range that circles earth.
mid ocean ridge totally this thing's huge
It could be called a trench, crevice, ocean ridge, or abyss.