The O2 is great, but what's the point in visiting an enormous marshmallow if you can't climb over it? Become a real explorer – you'll be given a suit, boots and a harness in preparation for clipping your way onto the walkway and heading up to the top. A climb guide will be with you every step the way to explain the 360 views of historic Greenwich, the Olympic Park and Canary Wharf. Over 10s only. Under 18s must be accompanied by an adult, with 1 adult for every 2 children. You must be at least 1.2m tall and not weigh over 21st/130kg/286lbs. Not suitable for pregnant climbers.