Water

4. Rise and fall of waves, gets bigger?
6. Ebb and flow of the sea.
7. Group of fish.
11. What pinnipeds are commonly known as?
12. Pearl giving mollusc.
13. Largest or saddest creature
14. Area surrounded by water.
16. The movement of water from one place to another, at this moment perhaps?
18. Roman god of the sea.
20. Where land and sea meet.

1. Chemical reaction that produces light energy within an organism's body, most commonly found in the ocean.
2. Dolphin place of learning.
3. Captain of a submarine or lost fish?
5. Mythical singers luring sailors to their deaths.
8. Greek goddess born from sea foam.
9. Release the …!
10. Flaming edible seaweed.
15. Marie Rose’s favourite seafood.
17. Traditionally what number wave is the most powerful?
19. Areas of sea floor covered in this seaweed are known as forests.