The Yukon Yak by Alpacka Raft> of Alaska is designed for back-country adventurers. It weighs an astonishing 3 pounds 12 ounces and fits easily in a backpack. It inflates to 68 inches long and 38 inches wide. It’s not a toy – seams are welded and the floor is made of 870-denier nylon ballistics cloth. $595. (907) 688-8005; AlpackaRaft.com.