Yachting came to mind when thinking of a sport for Y but it tends to be referred to as sailing. I had to delve deep to find alternatives but there were a few:
Yukigasson is the name for a snow balling game in Japan. Played with 7 a side the object is to hit your opponents with a snowball and eliminate them. They wear protective gear and that's not surprising as the snowballs are made in advance so they must be like chunks of ice!
If you don't like the cold you could go to Manipur in India and try Yubi Lakpi, a football game with similarities to rugby but played with a coconut.
Or, if like me you're a bit of a couch potato, you could always whip out a YoYo for a bit of fun without too much effort required!