It was Eustace. Reason being if he hadn't laid the last sword with the others on Alan's table then the darkness wouldn't have easily died or been defeated. I don't think Edmund stabbing the serpent had anything to do with the darkness being defeated.

^ I think it is definitly true that if Eustace had not put the swords together, the mist would not have been destroyed. ...

But why, after the swords are united, doesn't the mist immediately blow up? Why does it only happen after Edmund stabs the serpent?

Interesting point you've brought up.

After thinking about it, I think that yes, Edmund stabbing the sea serpent was the destruction of the mist.

But then what did the blue light that shot up into the sky do? Nothing? Or is this just another thing in the movie that doesn't make sense? (Probably the latter, I'm just wondering...)

But why, after the swords are united, doesn't the mist immediately blow up? Why does it only happen after Edmund stabs the serpent?

Maybe Edmund destroys the serpent, and Eustace puts the swords together, at the same time? Only, they show one at a time, so it looks like it's one after the other? It's been awhile since I've seen it, so I don't quite remember if that's a possibility or not.

Maybe they wanted the heroes to all conquer all the evils in one moment? The Edmund part might not have had to with destroying the Dark Island, per say. Maybe they just wanted to make the moment more climatic, and therefore had two triumphs take place at once -- the defeating of the dark island, and the defeating of the serpent, and it just hapenned to look like they were more connected to eachother than they are... It's a possibility anyway. Just thought I'd throw that out there.

I voted for Eustace destroying the Dark Island. Especially since Lucy indicates it was him. Unless both Edmund and Eustace destroyed the Dark Island, but "in different ways"... who knows. I thought that movie should have made a lot of things clearer than it did.

~Riella

I feel its when Eustace puts all the swords together the sea serpant is destroyed, because after he does it Edmunds sword turns all blue (Which I dont get that al all) so even though Edmund stabbed the SS which I think killed it, Eustace putting the swords together was the reason it ultamately was able to be destroyed, because in the scene earlier when they cut off a piece of an arm or something and it goes away into the air or something...meaning it couldnt be destroyed, it only worked after Eustace put the swords together, so actually I think the destroying the SS was a group effort

I hope I made sense....

Yeah it is confusing. I didn't vote because there is no "Teamwork!" option.

*Edmund killed the SS

*Eustace put the last sword down

*All of them gathered the other 6 swords

*Aslan made Eustace a human again so he could put the last sword down

*Aslan apparently gave them the swords in the first place.

They all played a big part in destroying it. I realize the question is who gave the death blow. I think what happened is that the swords destroyed Dark Island so nothing else bad could come from it. The crew just had to deal with what was already there.

If I recall correctly, they would do something to the SS that should have killed it, i.e. blow fire in its face, smash it into a giant rock, but the SS would only get worse, the hood would open it would grow tentacles. The thing just wouldn't die. Possibly because it was still able to feed off of nightmares because Dark Island still existed. Once Dark Island was destroyed, the SS couldn't feed off the nightmares and they just had to defeat it once more. It was on its last life in a sense. That was confusing to write out. I hope it makes sense.

I think what's more powerful is the symbolism behind that. You have Edmund overcoming his nightmare and rejecting the witch and you have Eustace battling the mist and doing what he can to save the rest of the crew even though he wasn't being attacked at that moment. Had he just left the sword alone the mist wouldn't have come after him and he could've taken the easy way out. But he chose to help his friends, which was a very heroic and un-predragon-Eustace thing to do. In that moment he conquered the selfish boy he had been. So I think it's a very powerful climax even if plotwise it doesn't make complete sense

I personally hope that Aslan was working in the background but Eustace played the largest (human) role in defeating the Dark Island. Edmund just finished off the serpent - his nightmare.

I think both had a role in it. Eustace started the process, and Edmund delivered the final blow. So both deserve credit for it.

I think Eustace destroyed the Dark Island's 'upper hand', as Coriakin put it. Eustace made the dark island defeatable. All that was left to do was defeat it, and Edmund did. Sort of like killing an immortal being; you have to make him mortal first and then kill him.

Though I'd like to take this moment to point out that all this is in direct contradiction to the book. In the film, Lucy says, "WE did it, I knew WE would." In the book, she tells the others, "I don't think it was us."

I think putting down the last sword is what destroyed the DI, since that was what Coriakin said. and besides why would they have to get the seven swords if just killing an encarnated nightmare would do it, it would make no sense that way.

Perhaps it took a collective effort? Eustace destroyed the green mist but the serpent had gained a life of its own feeding off the fear of the crew. I may be overanalyzing here

I am sure it was Eustace! I always think of it as being Eustace doing it because Aslan undragoned him and sent him to Ramundu's Island to put the last sword on the table.
I might see Dawn Treader again for the 4th time, so I will keep and eye out at this part!

I would have voted for a group effort too if there was a selection. But the triggering event was Eustace laying the last sword on the table.

I personally hope that Aslan was working in the background....

I interpreted the blueness of all the swords on the table, and Rhindon turning blue, and the blue tower of light going up from Dark Island to represent Aslan's power which was turned on by the last sword making it to the table. Also I thought I heard Edmund say "I don't think it was just us..." though I might have to see it again to make sure.

It was the Albatross. It must have been doing something after appearing then diappearing or becoming invisible.

I did vote for Eustace as that was the key to it all, according to Coriakin. Then they needed a cinematic slow death to finish off the sea serpent and have the mist slowly lift to see the freed Narnians.

Ulitmately, Aslan would have to be the ultimate power of good behind it all. (IMHO).

But why, after the swords are united, doesn't the mist immediately blow up? Why does it only happen after Edmund stabs the serpent?

My guess would be they wanted to give Edmund a moment to redeem himself after thinking the ugly and dangerous creature up.