Colder, Further, Tougher, Older To Islas Cíes Courtesy of Ned Denison, Ría de Vigo to Islas Cíes, Spain. As open water swimmers get older, some get tougher, go longer, and acclimate better. "If you assume that it is more difficult to swim further and faster in colder water, then open water swimming is one of the few sports in the world where you can get