This might be obvious to some folks, but I’m going to through this out there:
Remember that device we saw on Keamy’s arm that they were putting on right before the soldiers left the boat?
It’s likely that the radio interference that the boat was having was because of that device radioing back to the boat. What would it be transmitting? It’s not like Keamy has an EKG running back on the boat, right?
Well, not quite. What I think he does have is a heart monitor that’s been wired up so that if his heart stops, it’ll trigger the bomb they found on the boat, setting it off.
The real question is, if that’s going to happen, how do Sun and Aaron get away? The boat blows up, and since the island needs them both they survive, to be picked up in the water?