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Nurikabe puzzle
Mark the sea around the numbered islands. Keep the sea connected, avoid every 2×2 sea square, and give each clue an island of exactly its size.
Nurikabe puzzle grid
Fresh puzzles are checked locally for one solution. If generation reaches its safety limit, a verified puzzle is rotated for a different layout.
Rules
Each number starts one island containing exactly that many cells. Islands cannot touch by sides. Every other cell is sea: all sea cells must connect, and no 2×2 square may be entirely sea. Tap a blank cell to mark sea; tap it again to clear the mark. Numbered clues cannot be changed.
How do you solve a Nurikabe puzzle?
Each number belongs to one connected island with exactly that many cells. Islands cannot touch each other by a side. All remaining sea cells must connect, and four sea cells cannot form a 2×2 square. Tap a blank cell to mark it as sea; tap it again to clear it. Use Check board or ask for a one-cell hint.
Frequently asked questions
How do you solve a Nurikabe puzzle?
Each number belongs to one connected island with exactly that many cells. Islands cannot touch each other by a side. All remaining sea cells must connect, and four sea cells cannot form a 2×2 square. Tap a blank cell to mark it as sea; tap it again to clear it. Use Check board or ask for a one-cell hint.
Are my moves uploaded or saved?
No. Puzzle generation, checks and hints run in this browser. Your moves are not uploaded or saved by this tool.
What are the rules of Nurikabe?
Each numbered island has one clue and exactly the number of cells shown. Islands cannot touch by sides. The sea must be connected and cannot contain a 2×2 block.
Does every puzzle have one solution?
The generator accepts a fresh puzzle only after a bounded local search exhaustively proves that it has one solution. A verified fallback is used if generation reaches its limit.