What term is used for the underwater features that do not reach the ocean surface?

Seamounts are underwater mountains formed by volcanic activity that do not rise above the ocean surface. These geological features can be found in various oceanic regions and typically have steep slopes, rising sharply from the seabed. The term “seamount” specifically describes these submerged formations, which can vary significantly in size and shape.

In contrast, islands are landforms that rise above the surface of the ocean and are fully exposed. Atolls are ring-shaped coral reefs, islands, or series of islets that create lagoons, typically formed around seamounts or submerged volcanoes. Reefs refer to underwater structures usually made of coral, which can be close to the surface but do not qualify as seamounts if they are primarily composed of coral and do not originate from volcanic activity. Thus, the characteristics that define seamounts make them distinct from these other underwater features.