The Spring (1989)

Archeologists Andy and Matty uncover a diary written by a member of Ponce de Leon's search party that provides clues to the location of the Fountain of Youth. They go to Florida to search for the site but find themselves hounded by a slimy businessman out to profit from the spring and a voodoo acolyte searching for eternal life. Andy's search for clues brings him into contact with local painter Dyanne, who seems to know more about the spring than she is revealing.

Unfortunately the movie The Spring is not yet available on HBO Max.