This large national forest operated campground wasn't up to full operations from COVID when we visited last summer, so our bathroom was closed and we had to use porta potties, but otherwise it was my favorite campground, I think ever. Privacy, gigantic lichen-draped douglas firs and yellow cedars, tons of thimbleberry to snack on, and adjacent Cowlitz River to play in. With a little hiking, there is a swimming hole and you can jump off rocks into the freezing cold water. According to the kids, this is the coldest water they experienced on our whole PNW/coast trip. 

People were not worried about bears here (or anywhere in WA, really), in case you're traveling from a non-bear area and wondered about bear boxes. We mostly didn't get cell service at our site (Verizon), but my son got a call through to my husband a couple times on his older Samsung while my iPhone never got anything through. Water didn't taste great. Maybe bring a filter or your own water to drink.

Perfect proximity to Mt. Rainier. Really nice vibe in the campground and with the people. Just absolutely gorgeous and perfect.