Olympic Hot Springs 21.8 miles
The Olympic Hot Springs was a man made resort but the owners lease expired in 1966 at which the park removed the man made structures and let it go back to nature. The 2.4 mile hike is an easy and very scenic one as it is now the remains of the old paved road. There are some streams to cross which can be a bit tricky during snow melt season however most of them have log bridges with a rail. A Park pass is required to access the trail head and the road is often closed (check Olympic Hot Springs (Elwha) Road conditions at the site below) from washouts since the removal of the Elwha dam. Once a local secret, it can now be difficult to find a pool that's not occupied by others who are sometimes nude which is apparently legal in the National Park.
If you have good lighting, a night hike and soak under the huge bright stars can be an awesome experience, The best, deepest and hottest pool was all but gone until some friends and I hiked up with picks and shovels and rebuilt it. (Shown in the photo.)
It has a very hot stream falling into it and a cold stream within arms reach to cool down with. To locate it, stay on the main trail until you pass the last pool, then take the quite steep narrow trail to the right and climb probably an 8th of a mile where it ends at the pool. Shhhh don't spread the word.
Sol Duc Hot Springs 44.2 miles
The Sol Duc Hot Springs Resort is a man made facility consisting of a cold swimming pool, three hot spring pools and a children's warm pool. The resort is located in a valley just past Lake Crescent up the "Sol Duc Rd." on the left. It is also the location of several trail heads including the "Sol Duc Falls".