It might just be the best deal in the hiking world: the National Park System's $10 Senior Pass, which gets the bearer (those 62 and older) into all national parks and provides discounts at some national forest sites, campgrounds, and boat launches. But the pass is set to jump up to $80 sometime this year, so don't wait to lock yours in.
National Park Service Slashing Free Days Next Year
This year, the NPS waived entry fees 10 times. Next year they'll do it just 4.