Underwater! – Wikipedia

Partially filmed on location in Mexico and Hawaii, Underwater! was completed in a newly constructed underwater tank in an RKO Radio Pictures soundstage. It was the first RKO film released in Superscope. Lori Nelson claimed Howard Hughes wanted her for the lead and paid Universal Pictures for her use; however, Jane Russell owed RKO a film.

https://en.wikipedia.org/wiki/Underwater!