Controls
Choose Sea, Land or Erase, then select cells. Numbered cells are fixed land. Right-click marks land. Mark every remaining cell before checking.
The rules
Each separate land island contains exactly one number and exactly that many cells. Islands cannot touch edge-to-edge. All sea cells connect edge-to-edge, and no 2 × 2 square may be entirely sea. A 1 is a complete island: its neighbours must be sea.
Each board in this collection has been checked for a single solution. New puzzle changes the board; Start over clears this board. Progress lasts while this page stays open.