If you're heading to the Canadian ski resort of Whistler and the terrifying double-black runs don't give enough of a rush, you could try flinging yourself down the longest and highest zip wires in North America. The Ziptrek Ecotours activity centre (00 1 604 935 0001; www.ziptrek.com) has doubled its number of wires, offering 10 routes of up to 1,100ft.