Formed over 300 million years ago, the Catskill Mountains have more than 35 peaks over 3,500 feet, cover 6,000+ square miles, and provide 90% of New York City's water supply. For almost 200 years, the Catskills have been a tourist destination and a haven for artists. Pictured from south to north are Twin, Indian Head, Overlook, Round Top, Kaaterskill High Peak, North Mountain, and North Point.