I was misguided by the fake reviews in IMDb: see that all the good reviews belong to persons with only one review promoting this garbage.
The plot is ridiculous, absurd, unrealistic and absolutely unbelievable. A crew of watermen abducts persons in boats to grind their flesh and make bait for fishes and crabs. Six youngsters have their motor yacht sabotaged and they are stranded in the sea. The crew of a trawler rescues them and they drink spiked water and faint. When they wake up, they learn that they are trapped in an island and they have to fight against the sadistic men to survive.
A yacht that does not have batteries to support GPS and other safety systems; a guy that sabotages the boat, steals the supplies, water and flares in a couple of minutes; the watermen are practically indestructible; Mike insists in returning many times, inclusive when he is escaping in a small boat and Bret is wounded and he wants to return to seek medical supply. A question: what happened with the boat and Captain Ray? In the end, what else could I expect from a movie where Jason Mewes is the lead actor? My vote is three.
Title (Brazil): "Maré de Sangue" ("Tide of Blood")