Nurikabe Techniques

Seven techniques solve every Nurikabe puzzle on PeerPuzzles. Complete islands, squares between islands and squares out of reach find most of the wall; islands and walls with one way out, and the 2×2 rule, do the rest; what-if takes over from Medium on. Each page shows its technique on the same 8×8 puzzle from the game, at the moment it’s first needed, so you can follow one solve from page to page.

Medium level 8, the 8×8 every technique page follows. It takes 42 steps and needs all seven techniques.

How many of the game’s levels need each one, out of 50 in each track:

Technique	Easy 6×6	Medium 8×8	Hard 10×10
Complete islands	50	50	50
Between islands	42	49	50
Out of reach	50	50	50
An island with one way to grow	41	48	49
A wall with one way out	29	34	41
No pools	49	50	50
What if	0	44	50

“Needs” means the hints, which always use the simplest technique that works, used it at least once. For all seven in one place, with another worked puzzle, see how to solve Nurikabe.

Medium level 8, solved.

Guides

Nurikabe: Complete IslandsWhen a Nurikabe island has all its squares, every square around it is wall. A 1 is complete from the start. With a real example.
Nurikabe: Between IslandsA Nurikabe square touching two different islands would join them, so it's wall. How to spot it, with a real example.
Nurikabe: Out of ReachThe most used Nurikabe technique: a square no island can reach is wall. How to count an island's reach, with a real example.
Nurikabe: An Island With One Way to GrowWhen a Nurikabe island still needs squares and has only one square it could grow into, it grows there. With a real example.
Nurikabe: A Wall With One Way OutThe Nurikabe wall must be one piece. A piece of wall with only one way out, while there's wall elsewhere, goes that way. With a real example.
Nurikabe: No PoolsNo 2×2 block of Nurikabe wall is allowed, so a block with three walls has its fourth square in an island. With a real example.
Nurikabe: What If? Follow a Choice to a ContradictionWhen no simpler Nurikabe technique works, suppose a square is wall (or island), follow what it forces, and see whether a rule breaks. With a real example.