Biologics.

This is coolbert:

Bio-luminescent oceanic organisms as a means of anti-submarine warfare [ASW]. Who would have thought it!

"How the Navy Tried to Turn Bio-luminescence Against the Soviets"

Cold-War research that never came to fruition!

"For decades, during the Cold War, both the U.S. and the U.S.S.R. had a military interest in bio-luminescent organisms, which use a chemical reaction to produce a brief glow when they’re stimulated. The light of tiny ocean creatures had revealed on occasion the locations of submarines in World War I, and both militaries imagined that they might be able to use this natural phenomenon more systematically in anti-submarine warfare."

. . . .

"By the end of the Cold War, neither side had succeeded in turning bio-luminescence into a strategic advantage, though . . . The light-sensing technology wasn’t quite good enough to be of use; distinguishing bio-luminescence sparked by whales or schools of fish from bio-luminescence from submarine movement proved difficult."

Technology of the period not able to discriminate between a large animal [a whale] or a large group of animals [a school of fish] passing through a mass of "bio-luminescent oceanic organisms".

Such a method to detect submarines today might be possible given modern and advanced optical instruments? Who knows if this research continues?

coolbert.