Monstroid (1980)

Directed by Kenneth Hartford. Set in a small Caribbean island community, the story revolves around an American businessman, Dr. Sam Everette, who discovers that a local industrial company's toxic waste has mutated the marine life into a gigantic, monstrous creature. As the monstrous creature, resembling a massive octopus, begins terrorizing the island and its inhabitants, chaos ensues. Dr. Everette, along with the locals, must find a way to stop the creature before it destroys everything in its path.