Whether you enjoy open water swimming, surfing, or you are crazy enough to participate in triathlons, there comes a point when you have to jump out of the water and attempt to get dry and changed. A large, fluffy towel would be ideal, but it is bulky and heavy to carry around all day and it will take a long time to dry - foisty, damp-towel smell is not something you want to transfer to the rest of your gear!