I have fond memories of this film, and watching it now they come back as strong as ever. Not only does lovely Bond girl Shirley Eaton make an appearance, but the stars of many of my fave shows of the 60s are present and accounted for: Lloyd Bridges (Mike Nelson of Sea Hunt), Brian Kelly (dad to Flipper), Marshall Thompson (Daktari himself), and David McCallum (the ever-cool Illya Kuryakin of U.N.C.L.E.). Along with the superb Keenan Wynn these cast members make a good compliment of aquanauts traveling in a futuristic sub on a mission to plant earthquake detecting devices around the globe. There’s a solid script, just enough tension, and assured performances that supply a fun and diverting story. What really shines are the excellent underwater sequences courtesy of the Tors unit that set the standard for underwater action sequences (such as their Bond film sequences). Photographer Lamar Boren and director Ricou Browning do some of their best work here. The sub here is a real one (I found it decades later lying by the side of the interstate highway in south Florida next to an amusement park). It was built in 1956 by Martine Diving Bells of San Diego. Another nice part of this film are the great special effects by Project Unlimited (TV’s Outer Limits and the props from the original Star Trek). While all the film seems quite dated now, it was believable action in its day, the sort of thing that was a not-so-guilty pleasure for a kid like me back then, and still very enjoyable today. Note the excellent score by Harry Sukman, which was released as a soundtrack LP that is a rare find these days.