They've been busy with their swimming lessons, that's how they were able to pull out the dragon.
Yeah, they walked into the water and pulled out the dragon, with massive chains.
Whitewalker Bill: Yeah, uh huh. The
Dumbest Whitewalker, huh?
Whitewalker Mitch: Shut up Bill.
Whitewalker Bill: Who is laughing now?!
Whitewalker Mitch: Shut up Bill.
Whitewalker Bill: Who needs hundreds of feet of large steel link chains? Why would you be so stupid to bring those along?
Whitewalker Mitch: Shut up Bill.
Whitewalker Bill: Ain't getting no dragon without these chains I say. Who are the dumb ones now?
Whitewalker Mitch: *stabs himself with dragon glass*
Meanwhile while dragging the dragon out:
Whitewalker 1: You know, I just thought of something.
Whitewalker 2: What?
Whitewalker 1: We are walking at the bottom of the water.
Whitewalker 2: So?
Whitewalker 1: Why didn't we do this to get to those people and kill them?
Whitewalker 2: I never thought of that.
Script Writer: Hmm... neither did I.
Jon Snow: Dude, can you give us some flaming swords too, you selfish prick?!