Play Battleship Puzzle Online
Use row and column counts to locate a hidden fleet of ships. Ships can’t touch — not even diagonally. Pure logic, no guessing.
Created by Brian Hamilton
How to play Battleship Solitaire
Find the hidden fleet. The ships you are looking for are listed beside the board.
- The number beside each row and column is how many of its cells are ship.
- Ships are straight, horizontal or vertical, and come in the lengths listed.
- No two ships may touch — not side by side, and not at a corner. Every ship is surrounded by water.
- A few cells are revealed to start you off. Revealed water is as useful as revealed ship.
- Every puzzle has exactly one solution.
Controls: tap a cell to cycle it between empty, ship and water. Marking water is most of the work — about seven cells in ten are water.
Tap cells to place ships or water
The counts are the puzzle; the reveals are a nudge
Battleship Solitaire hides a known fleet on the grid. You are told exactly which ships are out there — their lengths are listed beside the board — and every row and column carries a number saying how many of its cells are ship. A handful of individual cells are revealed to start you off.
It is easy to treat those revealed cells as the clues and the numbers as background. It is the other way round. The counts constrain every line at once; the reveals only pin down a cell or two each. On a hard 6×6 you are given about two revealed cells out of thirty-six — and that is enough, because the counts do the rest.
Ships cannot touch, so every ship carries a moat
This is the rule that turns counts into deductions. No two ships may share an edge or a corner, which means every ship is surrounded by water on all sides, diagonals included. Place one ship and you have placed water in up to ten cells around it.
It also caps how full a line can be. On an 8×8 you can never have more than four ship cells in a row, because a fifth would have to touch one of the others. Measured across these boards, only 26% of lines are half full or more, and ship cells make up 30% of the grid — most of the board is water.
Which is why 65% of revealed cells are water, not ship. A revealed water cell looks like a wasted hint and is often the more useful one: it removes a possibility from a whole line at once, and it is usually placed where a ship would otherwise have fitted.
Start with the zeros, then the near-fulls
A row or column reading 0 is free: every cell in it is water, marked without any reasoning. 13% of all lines read zero, so most boards open with one or two of them.
At the other end, a line whose count leaves it nearly packed is just as forced. Because ships need a gap between them, a 6-wide row reading 3 has very few arrangements — and often only one once a revealed cell or a neighbouring line is taken into account. Work the extremes from both directions and the middle of the board fills itself in.
| Board | Easy | Medium | Hard |
|---|---|---|---|
| 6×6 (of 36 cells) | 12.6 | 5.9 | 2.0 |
| 8×8 (of 64 cells) | 22.2 | 11.9 | 4.8 |
Where solvers get stuck
Forgetting the diagonal. Two ships touching at a corner is the single most common illegal position. If you have placed a ship, mark the diagonals as water immediately — it is free information and it is easy to overlook later.
Ignoring the fleet list. The counts tell you how many ship cells are in a line, not how they group. A row reading 3 might be one ship of three, or a ship of two and a single — and the fleet list is what decides. If the only three-cell ship is already placed, that row cannot hold another one.
Marking only ships. Roughly seven cells in ten are water. Marking water is most of the work, and each mark narrows the lines it sits in.
Treating a revealed cell as a whole ship. A revealed ship cell is one cell of some ship; it might be the end of a four or a lone single. What it does tell you for certain is that all four of its diagonal neighbours are water.
Two things you can check about these puzzles
Every puzzle has exactly one solution. This was not true before. The generator revealed a fixed share of the ship cells — 35% on Easy, 18% on Medium, 6% on Hard — and checked nothing. Measured against an exhaustive counter, 10 boards in 54 had a single solution, and 8×8 on Medium and Hard managed 0 in 16, while the page promised a unique solution in two places.
Boards are now built the other way round. Since the row and column counts are always visible, the reveals start at none: while another solution still exists, a cell is revealed exactly where that rival disagrees with the real board, which kills it outright. The difference is stark — a Hard 6×6 now shows about two and a half cells, slightly fewer than the old version, and is unique every time instead of one time in four. 72 boards across both sizes and all three difficulties were re-checked against a separate counter written from the rules alone; all 72 were unique.
10×10 has been removed. Proving a 10×10 board unique took twenty to twenty-four seconds, and most attempts did not finish at all. 6×6 builds in a few milliseconds and 8×8 in about a second, so those are what the page offers. Two sizes that always work are better than three where one usually fails.
Battleship Solitaire and its relatives
This is the one-player version of the pen-and-paper game, published in puzzle collections as Bimaru or Solitaire Battleships. There is no opponent and no guessing: the fleet is fixed and the board is deducible.
It shares its line-counting with Nonograms, but the two pull in different directions. A Nonogram clue describes the runs within a single line, so each line can be worked almost independently. Battleship gives you a bare total per line and a global fleet, so the reasoning is spread across the whole grid at once — and the no-touching rule, which Nonograms has no equivalent of, is what ties the lines together.
More puzzles like this
If you like deducing from line counts, try these: