Well, you might say that you can swim and hike in here or there. But you'll find Xi'an different from the places come to your mind when you think of swimming and hiking. It's just NATURAL.
What's more, you can go fishing there. Not only fish, but also shrimp. Cycling around the lake is another relaxing thing you can do there. Bikes for single or two persons are available. Not very expensive. It worths the money. Especially when you ride along the lake right before the sunset, or after the sunrise, it would be GREAT!