Deep-sea searches today cross the public consciousness when planes go missing, but deep-sea exploration draws less public attention than space exploration. We don't know what's happening in the dark deep, the secret waters where espionage, technology and the ocean meet. But surely it's just as full of improbable adventure as ever.

Steve Weintz is a writer, filmmaker, artist, animator. Former firefighter, archaeologist, stuntman.

This first appeared in 2015.