Lose track of time underwater, and you could lose your life when your oxygen runs out. Luckily, the Eterna KonTiki Diver watch saves you from your own absentmindedness. It uses technology from the automotive industry to stay waterproof at 3,280 feet without tightly screwing down its winding stem (a step that users often forget with other mechanical diving watches).
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.