Everything here has been done before – even 30+ years ago – but the combination of elements makes the film interesting. A prison barge sinks and the survivors’ life boat breaks up on the rocks, leaving them stranded and seemingly alone on a remote island. They soon learn that they are not alone and eventually meet up with the island’s “caretaker”.
On the surface, the rest is standard mad scientist fare although the backstory to the reasons for the research keeps it interesting. The effects are what they are – 1970’s men in rubber suits and some fairly good miniatures. The acting ranges from good to awful. The sad thing is that this could have been better. The survivors’ first encounter with the “fishmen” made for some tense moments, but those are blown through and the few convicts to survive the open sea are dispatched too quickly for any sort of tension.
Pacing aside, it’s a watchable movie. You have to ready yourself for 1970s schlock, but with that mindset, you can do worse.