Dibble dabble
Dibble dabble is a great game to play in the pool: fun, simple enough for younger kids, challenging enough for older kids, and, unlike some of my other favorite pool games, not overly rough/dangerous. 😉
The human knot
A fun game for on land or in the pool, one I often played with siblings and cousins. Players stand in a circle, grab hands, and form a giant human knot that everyone tries to untangle together.