Intrepid looks around as he removes the scuba gear and slips out of his diving suit.
"Wow, this place is impressive," he says. "How does someone accomplish something on such a grand scale without anyone topside being the wiser?"
He looks to Aquaphibian and asks, "What now, Phib? The dead end, or the giant-sized door? Neither of which sounds too promising. But, now that I consider it, why would someone build a corridor that goes nowhere?"
"Not to step on your toes, big guy," Intrepid says, then turns to the others. "but I think it'd be good idea to take a closer look at that dead end."