Ok, so this park is not what I'd call a "destination", per se, but keep with me here. Let's set the scene: You're on your way to some really great whitewater adventure somewhere in the USA and find yourself driving on I-80 across southern Wyoming. Mile after mile of desolate sagebrush and desert are wearing away at the enthusiasm you had for this trip.
Then the worst hits, you realize you can't reach your true goal without a stop for the night, but it's early yet! All is not lost!! If you just have to stop anyway, stop in Green River, Wyoming. The City and Sweetwater County have joined up and created a small artificial white water park at Expedition Island Park on the Green River. This island is the site where Major Powell began his 1869 explorations of the Green River.
The park has two small man-made rapids and a bit of an obstacle course on the back channel ending on low dam. The rapids are nothing to get excited about, but you can get wet and get in a little practice for technique between dinner and sunset in the summer.
The park is actually open year round, as long as the river doesn't freeze, and is free to the public. There is a small change room/bathroom there as well.
This certainly isn't the best water on earth, but it often comes as a welcome relief after a day crossing the desert.
The town of Green River has pretty much all the services you'll need. However, there are no really good kayak supply stores in the area.
Green River, Wyoming is an old railroad and coal mining town, so directions are difficult. I recommend using maps.google.com, enter a search for "Island Park, Green River, Wyoming", be sure to turn on the hybrid option. There are signs to the park if you watch close and pay attention.
Put-ins and take-outs aren't really a big deal. Sand and gravel beaches are located above both of the main rapid areas and there are several approaches to the back channel on both ends of the island.
For more information contact the City of Green River, Wyoming: