Water ride NYC

I was driving in with a couple people into New York City, and I decided to ditch them for the train at the last minute before going into the tunnel, so that I could go on this underground water ride. From the subway, you could ride on an innertube over rapids, while people tickled your feet and butt from below. It was a little odd having strangers touch you, but I was assured that all the volunteer ticklers had a strict ethos of non-groping -- it was a community and everyone looked out for everyone else. At the end of the ride, you exited out into a nice cafe with free snacks and beverages and mingling.