Thus was born the Sea Devils, a team of aquatic heroes and their adversaries. The Sea Devils were 6-inch 'bendies' like Matt Mason who came with several hard plastic accoutrements necessary for underwater adventuring, as well as a few more elaborate battery- powered mechanisms. The protagonists were Commander Chuck Carter, in orange wetsuit, and his companion (rank unknown) Rick Riley, in basic black. Their main adversary was Kretar, who had his own pet shark named Zark. Although not a lot is known about this line, there is rumor that there were also available some sort of man-like creatures, almost certainly bad guys; aliens? sharkmen? Kretar's henchmen? Not enough information on this is available yet.
Alas, the toy line wasn't very popular and Mattel soon discontinued it. This explains why this particular group of toys is terribly hard to find on the aftermarket, and when found, expensive. And being bendies, the figures are naturally prone to broken internal wires, paint chipping, etc.
Known Sea Devils figures and their accessories: (all come in boxed sets to hold everything)
Comm. Chuck Carter - diving gear, Sea Jet, motor
Rick Riley - diving gear, Sea Jet, motor
Kretor and Zark - ?
Search and Rescue Set - Comm. Carter, diving gear, Aqualander (land-sea vehicle), Sea Jet, motor