The third of these Kevin Connor directed science-fiction outings for Doug McClure - this time as maritime explorers looking for the lost Atlantis. Peter Gilmore adds a little gravitas to this nautical yarn, as they descend to retrieve a golden statue from the depths and end up meeting a giant squid that gives them a bit more than they bargained for. They face lots of angry pre-historic beasties as they journey to meet the Atlantian illuminati - Cyd Charisse and Daniel Massey, no less. Yes, it is cheap - just like the other two, and the script was probably concocted on the back of a beer mat, but it is still a fun little diversion and the special effects are perfectly acceptable for the time.