Cliff, Pat and some navy guys take a boat out to search for the crabs. Cliff dons scuba gear and dives in because there are no other scuba divers in the British navy. Nope. Not a one.
They don't find anything. More crappy British tanks arrive.
Next day we learn that other divers are looking up and down the coast. Cliff fears they might overlook the enormous crab army because of inexperience. Cliff is clearly an idiot.
Cliff finds a big cave with the crabs sleeping. Do crabs sleep? What do they dream about? A sentry crab arrives and Cliff has to hide. Tension!
Back up top, Pat is worrying about Cliff. One of the navy guys gets ready to look for him. The other navy guy makes tea. Stupid assumptions bloom like kudzu. Diver Stan looks for Cliff. He assumes Cliff found some interesting plants and that's why he didn't come back. Stan is clearly as dumb as Cliff.
Stupid Assumption #612
He finds the cave and just assumes Cliff is in there? Or something? Then he finds crabs. Tension!