Diving for treasure has always been an enjoyable pool activity, and this is an especially good choice if you have smaller kids who want to be included. Anything that sinks can be a treasure, and it doesn't even have to be a competition if you have enough treasure for everyone who's playing. If you want to make it a little more challenging, have someone start at the bottom with a toothpick as the treasure. Why? Hope floats and so do toothpicks.