Best way to kill sea creatures?

[Burnrate]

I have a map with a lot of mountains and a lot of water. Almost every city is along the coast with rail and road along the coast. Makes for interesting play but the cities are constantly getting increased danger from creatures that swim close and it's hard to kill them off completely with aircraft or artillery.

Can I pay an MTH to clean up the waters or anything like that?

[mroyer]

My opponent in multiplayer says he used aircraft for a long period of time and eventually cleaned up most of the ocean threat. Seems like a huge investment (ammo, etc...) to me, but hey, he's ahead of me in victory points - so who knows.

For my solution, I literally lined the coast in critical areas, including logistic lanes, with "coastal defense" units. What are CD units? I create those by creating battle groups of three regular infantry models, and rename them - i.e., instead of 1st battle group, 1st coastal defense. We're 100 turns in and I have yet to have a CD unit be attacked by an ocean faring creature.

-Mark R.

[Overlord015]

As mroyer suggested, coastal garrisons, and airpower will be your primary means. You can also use artillery (tube, rocket, and guided) if you can't afford to strap bombs and rockets to cessnas or build light helicopters. And if something ticks you off enough or is too much even for your mid/late game forces you can just nuke them.

Honestly, the ammo investment is worth it IMO, it's a good way to help build experience for your pilots and Air HQ commanders, and testing your aircraft models during peacetime or wars where you can afford the diversion of forces. This has the benefit of allowing you to keep lighter coastal garrisons and patrols if you start trimming them off early and aggressively.