The ocean floor is a fascinating place on which there are many interesting features. Some notable ones that come to mind are volcanoes and trenches, but there are many others.
The continental shelf is the part of the ocean floor next to the edges of continents. Because it is so close to the shore, the ocean floor here has a gentle slope leading to deeper parts. The water in this part of the ocean floor is shallow.
The continental slope is between the continental shelf and the abyssal plain. Here, the ocean floor has a very steep slope with a sharp drop to the abyssal plain. The water here is deeper than the water on the continental shelf.
The abyssal plain forms most of the seafloor and is found 3-6 km below the surface of the water. Much of the abyssal plain is flat.
An oceanic trench is a deep canyon on the ocean floor. The deepest trench is the Mariana trench, which is around 11 km deep.
A seamount is a gigantic mountain or volcano that forms in the ocean. If the mountain is tall enough and pokes above the water, it is known as an island. There are around 35,000 large and 140,000 small seamounts.
Finally, the mid-ocean ridge is a mountain range that runs through all the earth's oceans. It is 64,000 km long, and keeps getting longer. It forms when tectonic plates pull apart, magma spews out and continues to form the mountain range.