Jackson Slate, famous treasure hunter, is out to find the legendary Lost Gold Of Cortez in the open waters off a secluded island in the Caribbean Sea. Using dynamite to blast his way through centuries of silt, new chasms are created reaching miles below the ancient ocean floor. From here, an ancient evil is released, that quickly, savagely, and without warning, destroys Jackson s boat and kills his crew. The sole survivor of the carnage, Jackson teams up with marine biologist, Sarah, to venture back to the site and investigate the horrific events. They extract an egg from the darkest depths of the ocean and take it back to the lab to investigate. But when it hatches, they realise they have awaken a deadly prehistoric monster, the P-Rex, which will stop at nothing until the entire island is destroyed...
Unfortunately the movie Poseidon Rex is not yet available on HBO Max.
| Directing | Mark L. Lester | Director |
| Production | Jeff Goldman | Executive Producer |
| Production | Felix McNulty | Executive Producer |
| Production | Mark L. Lester | Producer |
| Art | John 'Skip' Weaver | Production Design |
| Visual Effects | Yancy Calzada | Visual Effects |
| Visual Effects | Vanessa Evigan | Visual Effects Producer |
| Visual Effects | Christian McIntire | Visual Effects |
| Crew | Mike Searle | Stunt Double |
| Visual Effects | Scott Wheeler | Visual Effects Supervisor |
| Production | Anthony Fankhauser | Producer |
| Crew | Herbert Eagan | Stunt Double |
| Crew | Stephanie Tichenor | Stunt Double |
| Visual Effects | Kevin Lane | Visual Effects |
| Production | Stuart Alson | Executive Producer |
| Camera | Alexander Yellen | Director of Photography |
| Editing | Daniel Duncan | Editor |
| Costume & Make-Up | Carleigh Herbert | Makeup Department Head |
| Visual Effects | Joshua Graham | Visual Effects |
| Visual Effects | Howley Smoot | Visual Effects |
| Visual Effects | Ryan Carter | Digital Effects Producer |
| Costume & Make-Up | Jessica Lynn Mathis | Costume Design |
| Sound | Chris Cano | Original Music Composer |
| Writing | Rafael Jordan | Writer |
