This will be my first trip to Yellowstone National Park. Are there any good places to swim in the park? I know to keep the heck away from thermal features. And I've heard that most of the lakes and such are far too cold. So...is there a safe and relatively comfortable place to swim there?

The park service has a designated swim area on the firehole river. It was crouded a couple years ago, but a nice place to swim.

Boiling River along the North Entrance Road.

There, spring-fed streams from Mammoth run into the main channel, and there are numerous hot spots that are great to soak in.

Other ideas: hop into the Firehole River near a geyser runoff and get as close as you can take.

Yellowstone's lakes are cold, but the streams stay relatively warm because of the thermal features; many streams never freeze even in the harsh winter there.

But remember-- relatively.

Bob Sihler wrote:Boiling River along the North Entrance Road.
There, spring-fed streams from Mammoth run into the main channel, and there are numerous hot spots that are great to soak in.
Other ideas: hop into the Firehole River near a geyser runoff and get as close as you can take.

+1. I really enjoyed boiling river.

Only two places that I know of, both mentioned above.
Boiling River, north of Mammoth and the Firehole Canyon. 1/2 mile flat hike to the BR. Parking is the biggest issue on the Firehole. BR can get a bit too hot late in the season if flows in the Gardner are low. Firehole can be chilly when flows are high, early in the season. Can actually swim in the Firehole, BR is a good place to soak.

Best advice I can think of for both places - Get there early or late in the day to avoid crowds and parking issues.

Thanks, all!

Soak at Polecat Hotsprings jsut west of Flagg Ranch if the Park Service Sign doesn't scare you away. I had a blast playing in warm Boundary Creek beneath spectacular Dunanda Falls. People boogieboard on Cottonwood Creek at the Climbers Ranch when its really hot.