In the Cerro Castillo National Park you have some options:

1. Trekking for the day to the Laguna Cerro Castillo (difficulty: medium-high)

2. Las Horquetas Circuit (5 days and 4 nights)

In the link below I leave you a complete guide to the Trekking of Las Horquetas in the Cerro Castillo National Park – How to get there, description of the route, what to bring and more!