650-950 calories. Rock climbing is one of the more intense and difficult activities to undertake, due to how physically and mentally demanding it is. But it is a highly effective workout, as it works on strength and endurance and can be made easier or harder, depending on the "routes" you choose and the speed at which you complete them. If you're wary about trying it in the great outdoors, search for a local indoor rock climbing gym instead. There are routes for all levels and of course harnesses and belays for safety.