Sea Battle is a free online naval strategy game you can play instantly in your browser against a computer opponent named Otto, no download, no account, and no waiting for another player. Each side secretly places the standard 5-ship fleet (Carrier, Battleship, Cruiser, Submarine, Destroyer) on a 10x10 grid. Tap Enemy Waters to fire a shot; a hit is marked red, a miss is marked white, and sinking every cell of a ship reveals it fully. Otto fires back at your fleet after every shot, hunting randomly until a hit lands, then targeting the surrounding cells to finish off the ship. Play through 15 levels that make Otto's targeting sharper with every match, from scattered random shots early on to efficient grid-search patterns and precise follow-up salvos near the final match. Win a level to unlock the next opponent strength; Try Again starts a fresh match at the same difficulty.
How to play Sea Battle
- Both fleets are placed automatically at the start of each match: a 5-cell Carrier, 4-cell Battleship, 3-cell Cruiser, 3-cell Submarine, and 2-cell Destroyer, each hidden on a 10x10 grid.
- Tap any cell on the Enemy Waters grid to fire a shot there.
- A red cell means a hit; a white cell means a miss. Hitting every cell of a ship sinks it and reveals its full shape.
- After your shot, Otto fires back at your fleet, shown on the smaller Your Fleet grid below.
- Otto hunts randomly until a shot lands a hit, then targets the cells around that hit to track down and sink the rest of the ship.
- The first side to sink every ship in the opposing fleet wins the match.
- Clear a level to unlock the next one, where Otto searches the grid more efficiently and wastes fewer shots finishing off a hit ship.
Tips
- Once you land a hit, fire on the cells directly next to it before jumping elsewhere — ships only run in a straight line, so a neighboring hit narrows the search fast.
- If two hits line up, keep firing along that same line in both directions rather than starting a new search elsewhere.
- Firing in a checkerboard pattern across open water covers the board efficiently, since every ship is at least 2 cells long and can't hide between the gaps.
- Keep track of which ships are already sunk — if the Carrier and Battleship are both down, the remaining hits must belong to a shorter ship.
FAQ
Is Sea Battle free to play?
Yes. Sea Battle is completely free to play online with no download, no account, and no in-game purchases.
Does Sea Battle work on mobile?
Yes — tap a cell on Enemy Waters to fire a shot, so it works on phones, tablets, and desktop.
Is Sea Battle the same game as Battleship?
Sea Battle uses the same classic hidden-grid, hit-and-sink naval gameplay that pencil-and-paper players have long called by names like Sea Battle, Salvo, and Broadsides — the mechanic long predates any single brand name.
How does the computer opponent find my ships?
Otto fires randomly until a shot lands a hit, then targets the cells directly around that hit to track down and sink the rest of the ship — a strategy known as hunt-and-target.
How many levels does Sea Battle have?
There are 15 levels. Otto starts with scattered random shots on early levels, then searches the grid more efficiently and follows up hits more precisely as you advance.