Reddit reviews Hiking Hot Springs in the Pacific Northwest, 4th (Regional Hiking Series)

Here are some of my recommendations, taking into account that some of the mountain parks (Rainier, St Helens, and Crater Lake) will still be partially closed due to snow:

Columbia River Gorge - Just east of Portland, full of spectacular waterfalls and trails, some nice small-ish towns, and some hot springs (Bonneville, Carson, Wind River)

John Day Fossil Beds National Monument - and undervisited gem in Central Oregon, home of the beautiful Painted Hills, and you may even time it right to catch the spring wildflower bloom there

Oregon Caves National Monument - it's in far SW Oregon, and one of the few, if not only, limestone caves in the PNW.

Olympic NP - Beautiful coastline, rain forests, alpine scenery (still snow in the higher elevations, though)

A few other cave recommendations are Ape Cave near Mt St Helens, Craters of the Moon NM in Idaho, Lava River Cave near Bend, OR, and Lava Beds NM just over the Oregon Border in California.

For hot springs, I'd highly recommend this guidebook

There's probably no way you could even do all of these in 4 days, so you might want to pick an area and focus in on that. Or fly to Portland or Seattle and rent a car, the extra days might be worth the extra expense.

I was talking with my friend who did half of the trip with me and we went through all the fantastic things about Idaho together. He reminded me that the group of bad ass hot springs along a river deep in the woods where he stayed for 5 days. The hot springs were fantastic. The hot water flowed out of the hillside and into a pool where big rocks were circled. Another tiny stream of cold spring water ran right along it and you could move a single 5 pound rock to adjust the temperature of the natural hot tub. The sand below it was very hot and you could just bury your feet in it and relax for hours. If you got too hot you could just roll out of it and into the snow melt water river which was alongside it. A moose would walk up to us and drink from the river. 2 naked old men accompanied us for a few hours. When we got to Olympic National Park I spotted a book with a picture on the cover of the exact place where we were days before. The naked old men agreed that this was the best hot springs of any they've been to, and they've been to many.

My picture

The Book

Atop a random pile of giant boulders in the idaho forest.