Cannons are active on various islands and sea forts. But the cannons are not manned by skeletons on the various Fortress and Strongholds throughout the map, especially the defence towers.
I know these are vaults which offen need bosses killed on the island, but if your boating past them they should be active and cannoning you when you go past them via boat.
Maybe stop them cannoning when you are very close like on Sea Forts, which works well.
More threats in the world is better, liven things up a bit more also.
