Danielle Panabaker as Maddy

Matt Bush as Barry

Katrina Bowden as Shelby

Jean-Luc Bilodeau as Josh

David Koechner as Chet

Chris Zylka as Kyle

Adrian Martinez as Big Dave

Paul James Jordan as Travis

Meagan Tandy as Ashley

David Hasselhoff as David Hasselhoff

Christopher Lloyd as Mr. Goodman

Paul Scheer as Andrew

Gary Busey as Clayton

Clu Gulager as Mo

Sierra Fisk as Bethany

Matt Lintz as Freckled Boy

Sylvia Jefferies as Young Mother

Jenna Hurt as Rochelle

Rozlyn Papa as Dawn

Alisa Harris as Hysteric / Stocky Woman

Stacy Rabon as Fearful Woman

Nate Panning as Waterpark Patron

Kathy Sue Holtorf as Bimbo Lifeguard

Irina Voronina as Kiki

Ving Rhames as Deputy Fallon (uncredited)

Sarah Wilson as Massacre victim (uncredited)

Katie Garner as Lizzie the Lifeguard (uncredited)

Lilith Fury as Wet T-Shirt Girl (uncredited)

Tabitha Taylor as Lifeguard (uncredited)