Haeinsa, Buddhist temple in Gaya-myeon, South Korea.

Haeinsa is a Buddhist temple in Gaya-myeon, Hapcheon County, South Gyeongsang Province, spread across the slopes of Mount Gaya. The traditional Korean wooden buildings are linked by stone pathways and staircases that pass through several courtyards.

Suneung and Ijeong, monks of royal Daegaya descent, founded Haeinsa in 802 after returning from Tang China and healing King Aejang of Silla's wife; the king ordered its construction in gratitude. In the 10th century, abbot Huirang secured the patronage of Goryeo's founder Taejo, and the temple was later renovated in 1488, 1622 and 1644. A fire destroyed it in 1817, and it was rebuilt in 1818; a 1964 renovation uncovered a royal robe of Gwanghaegun and an inscription on a ridge beam.

Haeinsa is one of Korea's Three Jewels Temples, representing Dharma, the Buddha's teachings, because it guards the Tripitaka Koreana. Its name means 'Temple of the Ocean Seal', a term from the Avatamsaka Sutra. Visitors can join temple-stay programs, and since May 2023 entry has been free.

The site opens daily from sunrise to sunset, and a roughly 30-minute walk leads from the parking area to the main buildings. The paths are mostly uphill and accessed via stone steps, so sturdy footwear is advisable.

The storage halls for the woodblocks date from the 15th century and use different window sizes on the front and rear walls to regulate air circulation. This system keeps temperature and humidity stable without modern technology and has protected the blocks for centuries.