How to play Sea Battle
- Each player has a 10 × 10 sea and a fleet of five ships: one of 5 squares, one of 4, two of 3 and one of 2. Ships lie straight, across or up and down, and may not touch, not even at a corner.
- Hide your fleet. Press Shuffle until you like where your ships are, then press Ready. With two players, pass the device so your rival can hide theirs. No peeking!
- Take turns firing at a square of your rival's sea. A white splash means a miss. A burst means you hit a ship.
- A hit earns another shot. After a miss, it's your rival's turn.
- When every square of a ship has been hit, the ship sinks. The whole ship appears, and the water around it is marked, since no other ship can touch it.
- Sink all five of your rival's ships to win. Orange fires first in the first round, and the first shot switches every round.
Controls
| Device | How to play |
|---|---|
| Phone or tablet | Tap a square of your rival's sea to fire at it |
| Mouse | Click a square of your rival's sea |
| Keyboard | Use the arrow keys to aim, and Enter to fire |
The bigger board is your rival's sea, where you fire. The smaller one is your own fleet, with your rival's shots on it. Under each board, the little ships show which ships are still afloat.
Two players on one device: before each turn, a cover screen hides both boards. Hand the device to the player whose turn it is, and they press the button to show their boards. After a miss, the cover comes back for the next player.
Computer levels
The computer never looks at your fleet. It only knows where it has fired, what it hit and which of your ships are sunk, just like you.
| Level | How the computer plays |
|---|---|
| Easy | Fires at random, and only sometimes follows up a hit. Good for learning. |
| Medium | Searches every other square, like the dark squares of a checkerboard, and follows a line of hits until the ship sinks. |
| Hard | Searches the open water where your remaining ships have the most room, and follows a line of hits until the ship sinks. |
| Expert | Counts every way your remaining ships could still lie around its hits and misses, and always fires where a ship is most likely to be. Very hard to beat. |
Tips to win
- Search like a checkerboard. Every ship covers at least two squares in a row, so firing at every other square is sure to find every ship.
- Follow up a hit. Try the squares next to it. Once two hits line up, keep firing along that line in both directions.
- Use the sunk ships. Ships can't touch, so the water around a sunk ship is empty. The game marks it for you.
- Mind the gaps. When only the big ships are left, they can't fit into small spaces between your misses, so don't waste shots there.
- Keep your rival guessing. Shuffle your fleet every game, so a friend who remembers last game's layout can't use it.
About Sea Battle
Games of hidden ships on squared paper are around a hundred years old, much older than computers. Each player drew a fleet on a grid and called out squares to fire at, and the other player answered "hit" or "miss". There are many versions around the world, with different fleets and rules. In this one, ships may not touch and a hit earns another shot, as in many classic paper versions, which makes for quick, exciting games.
Questions
Is Sea Battle free?
Yes. It's free to play in your browser, with no download and no sign-up. There are never ads during a game.
How do two people play on one device?
Choose 2 Players. Each player hides their fleet in turn while the other looks away, then you take turns firing. A cover screen hides the boards every time the device changes hands, so nobody sees the other fleet.
Can I choose where my ships go?
You choose by shuffling: press Shuffle for a new layout that follows the rules, as many times as you like, and press Ready when you're happy with it.
Does a hit give me another shot?
Yes. You keep firing until you miss. Sinking a ship doesn't end your turn either.
Updated 6 November 2026