Photograph by Michael Yamashita. @yamashitaphoto - Today we celebrate 100 years of @nationalparkservice: I photographed Grand Prismatic Spring, the largest hot spring in the USA, from a helicopter flying over Yellowstone National Park at noon after the morning burn off of fog. The world's first national park, #Yellowstone encompasses over 2.2 million acres of forest and remains one of the world's foremost wildlife sanctuaries. #NPS100 #NPS #nationalpark #grandprismaticspring @natgeo @natgeocreative @thephotosociety