Since whales are teaming up with each other to take down yachts and teaching others how to do it I thought this would be a fun question.
If a majority of intelligent enough sea animals that could communicate with each other teamed up to mess with human activities in the sea who would win.
By the way for people that say that humans would obviously win we have already lost a war against emus before.
Things like tanks, guns, and flamethrowers aren’t going to work in the water. Even just the dolphins could take humans down. It would be like the emu war, just without the weaponry and with the enemies being smarter.
Boats, torpedos, depth chargers and harpoon will work quite well though.
I mean things every average combatant can wield.
A simple hand grenade then. Shockwave from even small explosions are much more lethal in an incompressible medium like water.
So as long as we keep lobbing explosives in the water while staying out of it itself, the marine mammels don’t have a chance.