“The Drowned City” by L. Ron Hubbard
Publication date: May 1935
Original publication: Top-Notch
Genre: Historical Fiction
Story description: A former boss becomes a dangerous adversary when two deep-sea divers decide to go their own way to search for hidden treasure in a city that is now beneath the sea.
Currently available as part of the Stories from the Golden Age series, in the title Mister Tidwell, Gunner.