Red Water (2003) on Netflix

Plot summary

Louisiana, a small oil rig on a river hits a big well, and fishing captain John Sanders, who left the oil fields after a blowout he ran killed four men, is hired with his friend Emery Brousard to carry his ex-wife Dr. Kelli Raymond and her boss Gene Bradley to the site. Body parts turn up in the water and a large bull shark has entered the river. Emery's people, a local tribe, hold the shark to be the physical form of a spirit that guards the well site, roused by the drilling. At the site the group finds an anchored boat they take for a rival oil company's, but the men aboard are criminals hunting stolen money sunk in the river, and Gene's confrontation with them leaves the group under threat.