Jaws 3-D (1984)

A great white shark attacks Florida Sea World in what is basically a name-only sequel to the first two Jaws movies, though continuity of a sort is maintained by having Chief Brody's two sons (who aged about ten years in the three years between Jaws and Jaws 2, and are now fully grown men) on hand. (Though this ostensibly helps set up the shark vendetta plot of Jaws - The Revenge, that movie for some reason gives the sons totally different back-stories.) 
Director Joe Alves was a key member of the production team on both previous Jaws movies, but anyone led by this, and Carl Gottlieb's screenwriting credit (to say nothing of Richard Matheson's), to expect a work of any real significance will be disappointed: it's a splashy, colourful adventure-disaster thriller, with an entirely different atmosphere to its predecessors.
It's also incomparably superior in the original 3-D format: due to the limitations of the process, the image quality in the flattened version issued to tv and video is distractingly poor, and many of the effects look weird.