Well, that too. [And Toothless is nothing if not protective; if anything remotely dangerous lies ahead in these tunnels, he'll know, and he'll react accordingly. It's always been reassuring for Hiccup, to have a 1700 pound dragon firmly on his side.]

If it narrows any more, we might have to turn around. Try another tunnel. [He's not super eager to go down any of them without Toothless.] What do you think, bud? Should we turn around? [Toothless lets out another burst of purple light, ringing down the length of the tunnel, and the dragon seems to nod his head to continue, rather than turn back.] Looks like it gets a little wider.

You're not planning on a fight, are you? Technically we're the invaders here.