Jack felt as though his head was full of cotton wool. And it became hard to tell exactly what was going on until they broke the surface and he took a very deep, much needed breath.

He looked around frantically, seeing the Doctor beside him, and he nodded, still catching his breath.

It struck him then, only briefly, that he might have yet again done something the Doctor didn't want him to. Was that his whole point? Did he want to get himself into trouble? Well Jack couldn't allow himself to find that out.

"You okay?" he asked when he finally had breath enough to. "I don't know what that thing was, but it was huge, I saw it."