Tucked onto the north end of Ririe Reservoir east of Idaho Falls, the Blacktail Day Use Area is eastern Idaho's go-to spot for cliff jumping and lakeside thrills. While the main reservoir draws boaters and swimmers, this rugged little park is all about the rocks — a string of cliffs above clear, deep water that has made it a summer rite of passage for adventurous locals.

From the south end of the parking lot, a trail leads down along the cliffs to a series of jumping spots that range from low, beginner-friendly ledges just above the water all the way up to dramatic perches as high as 80 feet. Whether you want a gentle splash or a serious leap, there's a launch point to match your nerve — and the same cliffs draw rock climbers looking to scramble the rugged shoreline.

Cliff jumping is genuinely dangerous, so use your head. Always check the water depth and watch for submerged or shifting rocks before you jump, since conditions and water levels change through the season. Start low, never dive headfirst, never jump into water you haven't checked, and skip the higher ledges unless you really know the spot. There are no lifeguards here, so look out for each other and know your limits.

The Blacktail Day Use Area is managed by Bonneville County, with a modest day-use fee (around $3 on weekdays and $5 on weekends and holidays). Summer is the season, when the water's warm and the cliffs are busy with sun-seekers; weekday mornings are quieter if you'd rather have a little more room.

Bring water, sun protection, and sturdy shoes for the rocky trail, pack out everything you bring in, and you'll see why this cliff-lined corner of Ririe Reservoir is one of eastern Idaho's most exhilarating summer hangouts.