An infrequently-visited trail off the Carbon River Road, the Old Mine Trail follows a short but steep roadbed to a mineshaft. It's a good outing for kids, if they're willing to make the short push up the steep section.
Just past the Carbon River Ranger Station, at the northwest entrance to Mount Rainier National Park, park your car and make your way down the flat, wide road converted to trail surrounded by greenery and the rushing of the river. After a bit more than a mile of hiking, look for a trail off to your right.
This is the route to the Old Mine, a steep push through close forests of Western Washington's signature western red cedar, Douglas fir, swordfern and fluffy moss. Luckily, the surroundings and the shortness of this uphill push make it bearable -- after just 0.3 miles you'll arrive at the mineshaft.
A hole in the hillside framed with ferns, the mine entrance is gated about a hundred feet in, so kids and curious adults can explore a bit in relative safety. There are some beat-up tracks, marking the beginning of the carts' journey into the earth to extract ore.
Look around the immediate area for other signs of human activity. Stumps and newer trees indicate areas that may have been cleared in the past as staging platforms for the exploratory mine activity.