The objective is to shade some cells, subject to the following rules:
- Each island will be part of an L-shaped polyomino exactly 1 cell wide.
- All shaded cells must form one stream, which is not allowed to contain "pools", i.e. 2x2 areas of shaded cells.
- Circles show the bend in the island with numbers in some circles showing how many cells make up that polyomino.
- Arrows are located at either end of the island and point towards the bend in it.
A standard 10x10 sashukabe puzzle and its solution.