I would consider river body surfing to be one of the ultimate water sensations and massages. Whirlpool baths and shower massages don't quite compare to the sensation and fun of laying in rapidly moving class 2 to 3 whitewater rapids.
Completely relaxing all of your muscles and laying on just moving water is an incredible feeling. All that is stopping you from floating down river is the bottom of your feet holding on to the rocks underwater. The weight of your body is balanced unto the moving water. You use your hands and arms to keep a balance. It takes a lot of practice, however, to get to where you can completely relax all of your body on a bed of moving water.
As you can see in the pictures, I am wearing a full wet suit.
OOOHHH bring back the early years before DNR stocked the river with trout. Ever since then, the dam gate near the lake bottom had to be left open all year to keep the river cold. During the early years of only dam overflow water, even clothes were optional:)and somewhat prefered. Since the push of the water tends to push down bathing trunks, short pants with a tight belt had to be worn(when people were around). The water was refreshing and the messages were incredible. Many warm summers were spent playing at the Gunpowder.
Having to wear a wet suit in this low 50s temp water, unfortunately, does take away from the body massage part of doing this :( Also, even with a wet suit and a warm day, it starts to get chilly after about 15 to 20 minutes. However, there are still enough variety of positions to keep it interesting and fun to do.
Really, this probably can be done in most other rivers with class 2 or 3 rapids. Warning..don't even think about doing this unless you are with someone with river experience and always wear a life jacket.
Sidenote: I'd say the most exciting and dangerous place that I had ever river climbed besides the Gunpowder would be at the top of Upper Yosemite falls in Yosemite National Park, California. I was standing behind the last smaller 20 foot waterfall before a pool of water that lead to the brink of about a 1500 foot drop. That is probably one of the nicer waterfalls to stand behind.
So, if your ever at the Gunpowder River below Prettyboy Dam and you see someone in a wet suit bobbling on and under a whitewater rapid...its probably me.