It should be cool to create battle with monster and towers in the island, instead of just towers. And we should able to see the battle. The monster could be the Yeti or something like this, and the tower could be more original than our own towers.
Just a guess, but I think he's either asking for an interactive battle with sea monsters, like we have with strongholds, or having sea monsters attack our islands.
Sorry for my english. "an interactive battle with sea monsters," Yes exactly or even interactive battle with monster on island.