A bus leaves every hour from El Bolson and will take you all the way into the park for A$ 7.50
There are local buses that will take you to El Bolson. Hitchhiking is also an option.
The park has some good hikes and a beautiful lake, surrounded by steep mountains. Entrance is A$25 for tourists, A$15 for locals. There is also an abundance of fruit trees, especially apples, within the park.
For A$250 you can take a 2-3 hour boat trip through the reservoir to Chile; the views are spectacular.