Yes we are dealing with Nazi's here. Nazi-Zombies to be exact and as far as I know this is the first Nazi-Zombie flick to take place under water.
Carradine has a bit more screen time then usual and the film makers definitely got their moneys worth from the old timer. Usually by this time Carradine would show up for a quick cameo, grab his paycheck and run. Then third rate film makers could slap his name to the title card and hope to sell more tickets to their B-movie. Not Shock Waves... John Carradine goes above and beyond. They get him in a bathing suit for his under water death scene and he is even carried by a group of young actors who leave the frail actor laying half nude on the beach.
Originally shot on Super 16mm and blown up to 35mm for theatrical release in true Texas Chainsaw Massacre fashion. Blue Underground's dvd release looks great. Check it out for a creepy time under water with zombies and a strange yellow scene with John Carradine.