Source: http://www.nps.gov/yose/parknews/use-of-...

Yosemite National Park advises visitors that the use of Unmanned Aircraft Systems (Drones) are prohibited within park boundaries due to regulations outlined in the Code of Federal Regulations (CFR). Specifically, the use of drones within the park boundaries is illegal under all circumstances. Thirty Six CFR 2.17(a)(3) states, “delivering or retrieving a person or object by parachute, helicopter, or other airborne means, except in emergencies involving public safety or serious property loss, or pursuant to the terms and conditions of a permit” is illegal. This applies to drones of all shapes and sizes.