HT Games
The Great Ice Cube Race
Have your children divide themselves up in to two teams. If you have an extra child, you can make them the referee of the first game. The children can then take turns being referee after that. Blow up two inner tubes and place one at each end of the pool. Next, set a plastic beach bucket inside each inner tubes. Each team will be assigned to one of these inner tubes. Have the referee say "go" and then throw a whole bunch of ice cubes into the middle of the pool. The teams will need to gather as many ice cubes as they can in 2 minutes and get them in to their plastic beach buckets. At the end of the two minutes the referee will need to count the number of ice cubes in each bucket. The team with the most ice cubes will be declared the winner.
Marco Polo
One pool game that has survived many generation is Marco Polo. In this game, one child is chosen to be the explorer. He is blindfolded and left to count to 30. During that time all of the other children must scatter around the pool. When the time is up, the explorer will shout "Marco" to which the children must respond "Polo." The explorer must use his ears to guide him to one of the children. The first person the explorer touches will become the new explorer. Make sure you designate whether players must remain in the spot they have chosen, or whether they are allowed to keep moving around the pool until they are found.
Scavenger Hunt
Find ten small items that do not float that are safe to throw in a pool, such as a toy snake or a spoon from the kitchen. Have the children cover their eyes as you throw these objects in the pool. Then give each child a different object to find. When you say "go," children can turn around and enter the pool and begin looking for their specific object. This will be hard because they will have to search through the other nine objects until they locate their own. The first child to bring you the object you chose for them, wins.