Normal sudoku rules apply. The nine cells containing a clue form an extra region, i.e. they contain the digits 1-9 without repetition. Shade some cells so that all of the following conditions are fulfilled: All shaded cells form one orthogonally connected area (water); Groups of orthogonally connected unshaded cells form islands. An island may consist of only one cell, and each island contains exactly one clue; No 2x2 may be fully shaded or fully unshaded. Each island acts as a killer cage, in which digits may not repeat and sum to the given clue (although for some of the cages the sum is unknown). Within an island, digits must either all increase or all decrease orthogonally in every direction, starting from the cell with the clue.