The oceans have risen, leaving little hospitable land, forcing the dwarves, orcs, and humans to fight it out over the few remaining places.
Maelstrom is set to release on Steam Early Access in April 2018, and is currently raising funding on Kickstarter.
They can also use various ammo types, like armor-breaking Iron Shot, sail-shredding Chain Shot, or crew-slaughtering Grape Shot to deal damage to certain areas.
These places indicate a huge beast coming to the map, and these various sea monsters will devour any ship that carelessly sails over these areas.