Diagonally adjacent clues

"Diagonally adjacent clues" is another basic technique used in Nurikabe puzzles. It revolves around the rule that all islands must be separated by walls.

When two clues are diagonally adjacent, it means that the squares touching both clues (which are horizontally or vertically adjacent to either clue) must be part of a wall. This ensures that the islands represented by the clues are kept separate.

This is how the technique is applied in practice:

Applying the "Diagonally adjacent clues" technique can help to identify walls and separate islands early in the solving process, making this a useful tool in the Nurikabe solver's toolkit.