The Patagonia Rivermaster II Vest is the only fly fishing vest you will ever need.  Constructed from 4-ply supplex nylon with a mesh liner for multi-climate comfort, the Rivermaster is also given a DWR finish for water resistance.  A padded collar reduces neck and shoulder fatigue when fully loaded.  Lots of perfectly-sized pockets will store more than enough fly boxes and accessories, while the generous rear stash with secondary "piggyback" pocket will accommodate a rain jacket and lunch.  The adjustable front closure allows for consistent fit no matter how you have layered beneath your vest.