Swap neighbouring sea creatures to line up three or more. Reach each level's goal before you run out of moves.
4 in a line → a blaster (striped) that clears its whole row or column.
L or T shape → a bubble bomb that clears the 3×3 around it.
5 in a line → a rainbow pearl: swap it with any creature to clear every one of that kind.
Out of moves? +5 moves can save a level once. Hint shows a good swap.