it's a huge depression on the sea floor formed when a plate sinks under another plate
It's a part of continent that extends beyond shoreline, under the ocean (it belongs to continent)
it's a big depression that extends from continental shelf to the sea floor
it's a huge mountain chain located in the centre of many of the Earth's oceans. The axis is called ocean rift.
Abyssal plain
Deep see trench
Mid ocean rigde
Continental slope
it's the bottom of the ocean where you can find the flattest areas on the Earth and mountains, volcanoes, Guyots, etc
Continental shelf
