This area has 1000 springs (beautiful in the springtime) and many hot springs! I grew up going to Banberries and Slagers, which are hot spring pools.
We have friends that camp here every summer, and I have seen it rated as one of the best places to go in Idaho.
Hagerman is one of the warmest places in Idaho so it is nice in the spring and fall when the mountain areas are too cold.
There are also fishponds to view/tour and an aligator farm.
Our family hiked at Hagerman in blazing sun, through a seemingly barren and desolate landscape. We didn't particularly enjoy the trip and haven't been back. There are many more enjoyable and picturesque places to hike, such as in the Sun Valley area.
The Snake River Valley is a hidden gem that most people will miss because they want to stay on the freeway. If you are east bound on I-84, get off at Bliss and take Hwy 30 and follow it through the valley, and past 1,000 Springs. Once you get to Twin Falls, you can catch the freeway again. West Bound on I-84 get off at Twin Falls on Hwy 93 and follow it to Hwy 30. For a better adventure, just get on Hwy 30 at Bliss on the west end or Burley on the east end and enjoy a trip through a wonderful area off the beaten path! Take some time to enjoy some of the small towns along the way and meet some wonderful people.