Two sisters, Amy and Jeni, write the Peppertowne blog. One loves furniture and chairs so I'm assuming she's the one who reworked this $8.00 upholstered chair into a waterproof tree swing. Though, I would probably add a seat belt of some sort to keep the kids from flying out. Jeni (I'm assuming) shows you how to waterproof this cushy swing, as well as how to string the chair securely onto the end of the ropes.
Read more about the chair, wood, wicker and fabric transformation at Peppertowne.