Story, first published: Astounding Science Fiction, May 1940
In "Rim of the Deep" ..., the only Simak story ever set on the ocean bottom, old prospector Gus saves the hero from sea-bottom pirates and, for good measure, helps the hero to squelch some Venusian aliens set on sabotaging our undersea colonies.
Ewald, Robert J.: When the Fires Burn High and the Wind is from the North, p.26-27