Normal sudoku rules apply. All cells are either island or water. Each shaded cell is an island cell; the number in it is the number of cells in that island. Each island must contain exactly one shaded cell, which contributes to a set of non-repeating digits that sum to the total in the shaded cell. Different islands may not touch orthogonally. The water cells are orthogonally connected and may not contain any 2×2 areas of water. Island totals are not necessarily in the top left most cell of an island.