From VIVOBAREFOOT, the lightest running shoe in the world has arrived! The Ultra, an amphibious three-in-one running, walking, camping, and water shoe. Weighing at 3.8 ounces without the insert sock-liner or tongue (0.2 ounces), and only 5.8 ounces with the sock-liner, the VIVOBAREFOOT Ultra is suitable for light trail cross training, water sports, long runs…