An American endurance athlete successfully completed a 40-kilometer swim Tuesday between Japan's two largest islands of Honshu and Hokkaido, achieving the feat of crossing seven difficult open water channels in the world, a support group said.After swimming across the Tsugaru Strait, which separates Japan's main island from Hokkaido in the country's far north, in 11 hours, 43 minutes and 35 seconds, Rob Lea, 45, became the world's first person to complete the "Double Seven" challenge -- seven channels and summits across seven continents, according to the group.The target channels for the "O…READ FULL ARTICLE