Fishing for Treasure
Hang a sheet from a doorway, and attach a piece of yarn to a long stick or yard stick. At the end of the stick, attach a small weight, magnet or close pin to weigh the line down. Each child takes a turn standing on one side of the sheet and "casting" her line through the doorway. An adult will be waiting, unseen, on the other side of the sheet. When the child casts her line, the adult attaches a small prize to the end of the line using the close pin or a piece of tape. A small piece of candy will work well. Once you attach the candy, give the line a tug so that the child knows she can now reel it in and claim her prize.
Bobbing for Treasure
Fill a baby pool with water outside as the main location for the game. Gather a variety of plastic fish. The fish should be solid so they cannot float. On the bottom of each fish, write a number with a permanent marker. Each number should correlate to a goody bag full of "treasure." Have each child take a turn bobbing for treasure fish and then collecting their goody bag of prizes that matches the fish he successfully got out of the pool.
Scavenger Hunt
For a pirate, mermaid or beach party, create a fish-themed scavenger hunt game. Trace outlines of a fish onto construction paper, and cut them out to create the clues. Write a clue on each fish. The clues should lead the players from one clue to the next in order. The clues can also be fish or sea life themed. For example, to lead the children to a fish tank, write, "This is where our pet fish calls home." To navigate the players to a whale stuffed animal write, "This creature is not a fish but swims in the sea." The player or team of players that reach the end of the scavenger hunt first finds a treasure chest full of chocolate gold coins.