I looked up this forum, and joined it, just to find out what others thought about Charlie's death. It struck me too as hugely dumb--he could easily have left the comm room, talked to Des for a while about why he couldn't go into a flooding room (the water would have pushed him out anyway), mosied over to the moonpool, dove in and and swum to the surface. It would have taken lots of time for the water to fill the whole station. The only plausible explanation I've read here so far is that he simply felt he had to die because of Des's vision that he had to die for Claire to live. So it really was a choice, a willed self-sacrifice without even the understanding of why he must die, since the situation itself did not require his death (like jumping in front of a bullet, e.g.). In this sense it was a nice contrast to the vengeful violence of most of the other non-others on the episode.