Firehole River offers the best dry fly fishing in the park with BWO, PMD and caddis life cycle patterns getting the most attention from trout. Be sure to try soft hackle versions of emerger patterns for these insects. Lewis River channel offers good streamer fishing for brown trout. Use generous insulating layers or insulated waders for comfort while wading the ultra-cold river water. Ice is off Shoshone Lake, but trails to it still have areas with snow and with muddy stretches. You will need a non-motorized boating permit and a free Yellowstone Park invasive species sticker on any floatation device to be used on the lake and on any park still water. Go to Yellowstone Park web site boating regulations page for details.