In 1997, Denver filmed an episode for the "Nature" series centering on the natural wonders that inspired many of his best-loved songs. His last song, "Yellowstone, Coming Home", composed while rafting along the Colorado River with his son and young daughter, is included. In the summer of 1997, shortly before his death, Denver recorded a children's train album for Sony Wonder, "All Aboard!", produced by longtime friend Roger Nichols. The album consisted of old-fashioned swing, big band, folk, bluegrass, and gospel music woven into a theme of railroad songs. It won a posthumous Best Musical Album For Children Grammy, Denver's only Grammy.