In the spirit of generosity in which Mother Earth (and violent volcanic eruptions) sculpted the country’s most beautiful natural areas, the National park Service has just announced its popular series of free admissions weekends for 2011.

More than 100 sites, including Mount Rainier National Park (just three hours away) and Oregon’s only National Park, Crater Lake, are set to let you in gratis. The fee waiver includes entrance fees, commercial tour fees, and transportation entrance fees. We’re pretty sure no one can even say, “fee” during these weekends.

No need to wait around until summer, either.

The first freebie is January 15-17—the perfect time to see sapphire waters of Crater Lake bounded by mountains of white. (The park gets an average of 533 inches of Cascade powder each year). And while facilities are limited at the park this time of year, rangers still lead daily snowshoe treks in the silent, winter wonderland.

For those planning ahead for balmier days, the additional dates are April 16-24, June 21, September 24, and November 11-13. Which should give you plenty of time to start planning your own Ken Burns-style documentary of your National Park experience.