I have not come across a specific term. I think they are simply called underwater plateaus.
It could be an ocean plateau. I didn't find anything other term either.
seamount
I need an answerer
An underwater plateau is called a seamount. A seamount is a mountain rising from the ocean floor that does not reach the water's surface. These submerged mountains are usually the result of volcanic activity. To verify this information, you can search for "What is an underwater plateau called?" on a search engine, such as Google, or refer to reputable online sources about marine geology or oceanography.
