var brightcovevideoid = '3516382888001'; Best posse ever? Open-water swimmer Adam Walker was swimming New Zealand's Cook Strait April 22 as part of the Oceans Seven mission when he noticed a fairly unwelcome guest accompanying him on a swim: A great white shark. Fortunately, someone - or rather, several someones - had his back. Cook said he was surrounded by a pod of 10 dolphins, who continued swimming with him until the shark - no doubt intimidated by the show of strength - took off. "I'd like to think they were protecting me and guiding me home," Walker wrote on his Facebook. Walker's...