I often get emails asking what I recommend during trips to Boise. Now that I've lived here about 2 years, I feel like I'm starting to get to know this fun little city so I think I might actually start making recommendations.
For summertime, that's an easy one. Roaring Springs Waterpark!
(I didn't take that top right photo. Obviously I did not have access to a helicopter while visiting.)
We went for the first time this summer just last weekend and had so much fun. It is just a great place to spend a hot day. Even I had a blast, and I'm supposed to be "taking it easy". I relaxed on a shaded lounge chair, floated down the lazy river and swam with Lydia in the wave pool. Even when it's packed, it doesn't matter. Its a huge place with lots of room.
Shane and the kids had a bit more active of a time, hitting the slides (Collin stuck to the kiddie ones) and running around the kids area. Shane and Lydia did most of the bigger attractions and loved them. We got there right at opening (11am) and stayed until after 6. We went through a full bottle of sunscreen and gorged on hamburgers, soda and snow cones. It was one of the best days.
I highly recommend making it part of your Boise summer plans.