a nurikabe puzzle.
here is the puzzle:
some necessary seas:
now, consider the following diagram:
8 must be able to reach at least one cell in the red square, otherwise a whirlpool will be created; similarly for 6 and the blue square. now, note that 8 cannot pass through the shaded red square because it is adjacent to the 2; therefore, the two Xs are unreachable, and so the 8 must connect to the red circle. from here, the three blue Xs are unreachable because they are too far away from the blue 2x2. therefore, we arrive at the following configuration:
(we know that the 8 island cannot go through r3c3, otherwise a 2x2 whirlpool will be formed in the upper left)
from here, we can pretty easily deduce the final solution:
