And that? That made Jack's already impossibly wide grin even impossibly wider.

"You know, Doctor, I think we are."

A step behind the Doctor he ran, just as fast, beaming as he did. "This is more like it!" he grinned as they made down the corridor. The salty smell got stronger and stronger, and the curve of the walls seemed even more dramatic as they advanced along.

"Doctor, do you hear that?" Jack called aloud. Around them he could hear a flow like pipes, behind the walls, like water trapped behind a dam. He recognised the sound from the Hub. Sometimes, when it was quiet, you could hear the flow of the bay outside..