How 18 daredevils across the world get their adrenaline fix

For some people, the regular activities of everyday life are just not enough to keep the blood flowing. Sitting at an office desk, taking the train, drinking your coffee - they can only provide you with so much of a rush.

Extreme thrill-seekers will do everything from leaping off bridges to diving with sharks to get the adrenaline fix they need.

Certain activities are done in groups, like drift racing or waterfall jumping, but some are solo efforts for those who are just brave - or crazy - enough.