What is this Sea Monster Movie?

I saw a movie in either 1993 or 1994 about this group of people who were involved in a plane crash and ended up adrift on the lifeboat. There was a girl named Ariel and 2 brothers or best friends named Rick and Vick. They finally land on an island and Rick is attacked in the water by a creature which later turns him into that sea creature. Vick later on slices his arm on a leaf which causes hallucinations and because of this he almost kills a woman from the local tribe. He also starts to become the sea monster, but unlike his Rick, does not fully succumb to it and by the end he kills Rick and is cured. Please, what is this movie???