Seamounts and Guyots are volcanoes that have built up from the ocean floor, sometimes to sea level or above. Guyots are seamounts that have built above sea level. Erosion by waves destroyed the top of the seamount resulting in a flattened shape. Due to the movement of the ocean floor away from oceanic ridges, the sea floor gradually sinks and the flattened guyots are submerged to become undersea flat-topped peaks. We know that the tops of guyots were once at the surface because they contain evidence of fossils such as coral reefs that only live in shallow water. Seamounts conversely represent volcanoes that did not reach sea level so their tops remain intact and are shaped like volcanoes on land.

A volcano erupts above sea level somewhere in the ocean

After a long time, waves have eroded the portion above sea level.


A Gradually the sea floor subsides as it moves away from the oceanic ridge, and the guyot becomes submerged.

A seamount never reaches the surface so it maintains a “volcanic” shape. .