Last updated: March 29, 2026
Build numbered islands and one connected sea while avoiding 2x2 blocks of shaded cells.
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Nurikabe appeared in Nikoli in March 1991 and takes its name from a wall-like figure in Japanese folklore. The puzzle asks you to divide a grid into numbered islands and one connected sea. The numbers tell you each island's size, while the shaded sea must connect without forming any 2x2 pools. It looks calm. It bites later. The main challenge is balancing island growth against sea connectivity. Start by expanding certain islands and marking cells that cannot reach any clue.
A 2 clue already has one connected white neighbor. The island is complete, so every side cell around that two-cell island must be sea.
Three cells in a 2x2 square are shaded. The last cell cannot be shaded, or the sea would form a forbidden pool.
A blank cell sits too far from every unfinished island and is boxed away by completed islands. It must join the sea.
Play Nurikabe online for free. Grow islands, connect the sea, and avoid 2x2 shaded pools. Begin with small grids, then move to larger puzzles once island-size logic feels natural.
| Version | Difficulty | Players | Typical Time |
|---|---|---|---|
| Small Nurikabe | Easy | 1 | 8 to 12 min |
| Medium Nurikabe | Medium | 1 | 12 to 20 min |
| Large Nurikabe | Hard | 1 | 20 to 35 min |
Yes. Islands cannot touch by sides, but diagonal contact is allowed.
It is a square of four shaded cells. Nurikabe rules forbid that shape in the sea.
No. Each island must contain exactly one numbered clue.
Begin with the smallest clues and the most cramped spaces. A 1 clue is already complete, so every side neighbor around it must be sea. A 2 clue on an edge often has only one or two ways to grow. After marking those forced cells, scan every 2x2 area so the sea never forms a square pool. That early cleanup usually exposes the first large-island route. If two numbered islands would touch by growing into the same cell, that cell belongs to the sea. Recheck sea connectivity after each island grows. Mark unsure cells lightly.
Nurikabe turns a grid into a clean island-and-sea deduction puzzle. Count island sizes, keep the sea connected, and stop every 2x2 pool before it forms.
Every properly constructed nonogram has exactly one solution, and you can find it through logic alone. Three techniques: overlap, edge logic, and elimination. No guessing required.
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