Parks on the Air (POTA) is an amateur radio activity where operators set up radio equipment at parks, forests, trails, and other public lands, then make contact with other radio operators around the world, even with Astronauts on the International Space Station which is more the 200 miles above the earth. Radio Contacts are even made with Pilot of Commercial Flights and with sailors on ships and boats far out in the oceans or inland waterways of various countries.
Every park has its own reference number, and activators earn credit and sometimes awards from the parks they operate from.