Just outside the tiny hamlet of Kelly, on the quiet east side of Grand Teton National Park, Kelly Warm Spring offers one of the easiest payoffs in the whole valley. Pull off the Gros Ventre Road and you're met with a glassy, spring-fed pond framed by open sagebrush meadow, with the jagged Teton Range rising beyond. No hike is required — it's right at the roadside — which makes it a favorite for a picnic, a photo, and a little wildlife watching. Bison and elk often graze the surrounding flats, and the grassy banks make an easy, family-friendly place to spread a blanket.

The spring bubbles up at a steady 70 to 80°F year-round, and that warmth has given it a famous quirk. For decades, people have (illegally) dumped unwanted aquarium pets here, so the pond now teems with goldfish, guppies, mollies, swordtails, and other tropical fish you'd never expect to find in the high country of Wyoming. Watching them dart through the clear shallows is a hit with kids. The calm, warm water has also long made the spring a popular place for kayakers and paddleboarders to practice their rolls and paddle strokes in a forgiving setting before tackling colder, moving water elsewhere in the valley.

The National Park Service warns visitors not to swim, wade, or submerge their heads in the water here. As inviting as it looks, the warm, nutrient-rich pond carries high levels of E. coli bacteria and can harbor Naegleria fowleri, a rare but often-fatal amoeba that infects through the nose. That's why the Park Service recommends enjoying Kelly Warm Spring from the bank — looking, picnicking, and watching the wildlife rather than getting in. The park also asks visitors to leave the fish be and never release more; introducing aquarium animals is illegal and harmful, and the Park Service works to manage the non-native population.

The little town of Kelly just up the road has a surprisingly dramatic past. In 1925, the massive Gros Ventre Slide — one of the largest landslides in U.S. history — roared down the valley and dammed the Gros Ventre River, creating Lower Slide Lake. Two years later, in 1927, that natural dam failed catastrophically, and the resulting flood swept through Kelly, destroying much of the town and taking six lives. Today it's a peaceful crossroads, and the slide's raw scar is still plainly visible on the mountainside to the east.

Access couldn't be simpler: restrooms and interpretive signs are on site, and the spring sits right off the road. It pairs perfectly with other nearby stops — the historic homesteads of Mormon Row, the Gros Ventre Campground, and the drive out to Lower Slide Lake. Come for the Teton views, the improbable tropical fish, and one of the most effortless, scenic pull-offs in all of Jackson Hole.