At Bear Lake State Park on the Utah/Idaho border, we were the only ones there for two of three nights, and miraculously I found it relaxing and just lovely.
Known as the Caribbean of the Rockies for its blue water, Bear Lake didn't disappoint but unfortunately I can't say that the water temperature was Caribbeanesque.
When we rented a massive water trampoline, we also had to rent a paddleboat to shuttle us (save for Riley and Jackson, the two hearty souls who braved the icy swim) back and forth. Other than my nearly broken nose from Kenyon's head accidentally bashing me, the trampolining was great fun.
This area is known for its World Famous Raspberry Shakes, and we managed to have a few during our time there.
We spent a leisurely, pleasant three days there exploring.
Quintessential summer, and a perfect way to cool down after the heat at Arches.