An idea for phase 2.
How about barbarian water units such as: Sea Dragon, Kraken, Sea Serpents Saughin and others, these could roam the oceans looking for ships to sink and improvements to ruin. I would suggest that a couple are coastal water only (Sea Serpents and Saughin) Kraken are deap sea only and Sea Dragons can roam all water.
You could add in something for Naval civs where they can tame these beasts rather than land animals.
How about barbarian water units such as: Sea Dragon, Kraken, Sea Serpents Saughin and others, these could roam the oceans looking for ships to sink and improvements to ruin. I would suggest that a couple are coastal water only (Sea Serpents and Saughin) Kraken are deap sea only and Sea Dragons can roam all water.
You could add in something for Naval civs where they can tame these beasts rather than land animals.