These regions, formed by diverging plate boundaries, are below sea level and hold the majority of earth's water and contain features such as ocean ridges and deep
sea trenches.
Mariana Trench
Land Rifts
Ocean Basin
Sea Caves

sea caves.

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Ocean Basin

Explanation:

Ocean basin, any of several vast submarine regions that collectively cover nearly three-quarters of Earth's surface. Together they contain the overwhelming majority of all water on the planet and have an average depth of almost 4 km (about 2.5 miles).

from Britannica.com

within these regions are all the major types of biomes in the world. a biome is a community of animals and plants spreading over an extensive area with a relatively uniform climate. some diverse biomes represented in north america include desert, grassland, tundra, and coral reefs.