Jeongseok Airport — Jeju Island, South Korea

JDG designates Jeongseok Airport, a smaller airfield located on Jeju Island in South Korea, distinct from the much larger and busier Jeju International Airport that dominates the island's air traffic. Jeongseok has historically served a more limited role, including military use, flight training, and standby or backup airport functions for the island rather than regular high-volume commercial passenger service. Jeju Island itself is South Korea's most popular domestic tourist destination, known for its volcanic landscapes, beaches, and mild climate, but the bulk of that tourist traffic flows through the main Jeju airport rather than JDG. As such, JDG functions more as auxiliary aviation infrastructure supporting the island's broader air transport needs.