oceanagraphy

6. The deepest layer of the ocean, found in ocean trenches.
9. Ridge An underwater mountain range formed by plate tectonics.
10. A layer in a body of water where the temperature changes rapidly with depth.
11. The uppermost layer of the ocean, where sunlight penetrates.
12. Reef A diverse underwater ecosystem held together by calcium carbonate structures secreted by corals.
13. Shelf The extended perimeter of each continent, which lies submerged under relatively shallow seas.
14. A flat, almost level area of the deep-ocean basin.
15. A series of ocean waves with extremely long wavelengths caused by large-scale disturbances.
17. An underwater mountain rising from the ocean floor that does not reach the surface.
19. Aquatic animals that can swim and move independently of water currents.
20. The deep ocean layer, where no sunlight reaches.

1. The middle layer of the ocean, receiving very little light.
2. An opening in the sea floor out of which heated mineral-rich water flows.
3. The layer of the ocean at depths between 4,000 and 6,000 meters.
4. The rising of cold, nutrient-rich water from deep in the ocean to the surface.
5. Small and microscopic organisms drifting or floating in the sea.
7. Organisms that live on, in, or near the seabed.
8. The steep slope where the continental shelf drops to the deep ocean floor.
16. The concentration of salts in water.
18. A deep, narrow depression in the ocean floor, often caused by tectonic activity.