When a crop of doped-up athletes from the Lakecrest College swim team dive into the campus lake to blow off some steam, the bloodsucking leeches below the surface undergo a stunning transformation. After ingesting small amounts of the swimmers' steroid-laced blood, the slimy creatures grow to unusual sizes and set out to sink their teeth into an unsuspecting student population.
Practical Effects
Gloriously rubbery leech puppets
Costume
The entire male cast in tiny speedos

Director
David DeCoteau
Trivia, insights & behind the scenes
David DeCoteau directed over 130 films, many featuring shirtless men in horror scenarios—this is his brand.
The 'swimming in underwear' keyword isn't misleading—the cast spends 70% of runtime nearly naked for no plot reason.