Nurikabe

Nurikabe (Islands, Islands in the Stream, Streaming Content, Stream Island) is a Japanese logic puzzle. Blacken some cells to create islands of a given size.

Rules: Colour the grey cells of the grid black or white. The black cells divide the grid into areas of orthogonally contiguous white cells. The white areas must not touch each other orthogonally (but diagonally). A cell with a number is always white; to each white area belongs exactly one cell with a number. The number indicates the number of cells that form the white area.
The black cells must not cover an area of size 2×2 anywhere. All black cells must form a single orthogonally contiguous area.