Concept: one of those “hyper-intelligent shark terrorises scientists at offshore research facility” movies (can you believe that’s an actual genre?), except partway through the movie it turns out that the facility’s director is secretly the leader of an apocalypse cult and is trying to summon Cthulhu, and the shark is trying to stop him. In the end, the interns team up with the shark to bring down the cult and its master.
Huh, that fact about the Goliath dire Blaziken where natural resources couldn't sustain them optimally reminded me a theory about the Megaladon shark. Some scientists theorize great white sharks could grow into the size of their ancient ancestors, but can't due to lack of food, among other environmental factors.