Mermaids and sea monsters have successfully come ashore. You could add Sirens and other mythical creatures that inhabit archipelagos in seas and oceans.
The schools of magic in the fourth game are tied to races, which are recreated based on the principle of opposition: life and death, order and chaos, nature and destructive force. In my opinion, you could informally tie the 4 elements to the races: chaos - fire, life - water, order - air, death - earth.