A game that we had great success with, was a dry version of marco polo, but it needs to be played at night.
You can create an arena using tables turned on their side (this also helps with safety).
Then you pick who starts as "it" turn off the lights & play like you were in the pool.
When someone is tagged, they , as well as the one searching, say out loud "FREEZE". At this point you turn on the lights. No one is allowed to move again until the lights go back out.
Its easy, free & the Teens loved it.