Oceanography

3. The deep ocean layer, where no sunlight reaches
5. An opening in the sea floor out of which heated mineral-rich water flows
6. A layer in a body of water where the temperature changes rapidly with depth
8. The uppermost layer of the ocean, where sunlight penetrates
13. A series of ocean waves with extremely long wavelengths caused by large-scale disturbances
14. Organisms that live on, in, or near the seabed
16. A flat, almost level area of the deep-ocean basin.
19. A deep, narrow depression in the ocean floor, often caused by tectonic activity
20. Aquatic animals that can swim and move independently of water currents

1. The layer of the ocean at depths between 4,000 and 6,000 meters
2. A diverse underwater ecosystem held together by calcium carbonate structures secreted by corals
4. The steep slope where the continental shelf drops to the deep ocean floor
7. The rising of cold, nutrient-rich water from deep in the ocean to the surface
9. The extended perimeter of each continent, which lies submerged under relatively shallow seas
10. The deepest layer of the ocean, found in ocean trenches
11. An underwater mountain range formed by plate tectonics
12. The middle layer of the ocean, receiving very little light
15. Small and microscopic organisms drifting or floating in the sea
17. The concentration of salts in water
18. An underwater mountain rising from the ocean floor that does not reach the surface