Having watched episode 5x15 I think it’s become clear how Jack is going to save them. At the moment the bomb is situated underground through a network of tunnels, which I’m assuming have become blocked off, that’s why they had to swim through to it. In the finale Jack will have to transport the bomb through the tunnels and out to the Swan site (the bomb is conveniently on wheels)I believe Richard will unblock the tunnels allowing Jacks passage out into the jungle. From here on out is where the drama will come, as Jack tries to desperately get the H bomb out to the Swan site on time. Since from Daniels Journal, they know the exact time of the Swan explosion. They can in theory set the H bomb to detonate at exactly the same time. This is where it gets interesting for me, we know the island is unique and we can assume all the energy generated by it is negative in nature. This negative pulse of electromagneti! c energy from the Swan explosion will cancel out the positive electromagnetic pulse from the H bomb.
