John thinks for a moment then moves closer to Ianto, holding out a hand to him.

"It's pretty sensible to be afraid of water, but there's no tide here. No waves. If you don't trust the water, trust me. I've had water egress training. That means they strap me upside down in a fake cockpit, throw me in a pool and I have to get myself out. If I can get myself out of that, I can definitely get you out of here without breaking a sweat."

So, if you want to try and practice swimming without drowning? John is okay with helping you out here. There's no better place to try it, after all. This is much safer than the ocean.