Originally Posted by the_marq

Did he blow up the sub really? We see him inside the sub with the explosives, then the it cuts away. The next time we see Locke he is strolling down the pier, soaking wet as if he had been swimming in his clothes. Then the others show up, there's shouting, machismo... yadda yadda yadda. Then BOOM. Something blows up a few hundred metres away.

Why would Locke have been swimming to plant the bomb? Unless he happened to have a couple magnets there would be no way to attach the bomb securely to the outside of the boat. It would have been far easier to blow it up from the inside.

Theory: he piloted the sub away a few hundred meteres then swam back to the dock and then blew up some random debris to make it appear the sub is gone, when in fact it's just parked down the beach.