An undersea volcanic formation that does not rise 1000 meters above the surrounding sea floor is called a seamount.

Here's why:

* Seamount: A seamount is an isolated underwater mountain rising at least 1000 meters (3,281 feet) from the seabed.

* Guyot: A guyot is a flat-topped seamount, formed by erosion from waves and currents when it was once at or near sea level.

* Volcanic cone: This is a general term for any cone-shaped structure formed by volcanic activity.

* Submarine volcano: This is a general term for any volcano that erupts underwater.

The key difference is that a seamount must rise at least 1000 meters from the seabed to be classified as such.