Ganghwa-do 강화도 Korea's most historic island, with several sacred mountains
Ganghwa-do is a County of Incheon City and Korea's fifth-largest island, at 305 sq km (422 if you count all the smaller islands around it). It sits right at the mouth of the Han River, separated from the Gimpo Peninsula by only a narrow channel -- through which the water can be quite treacherous -- a large and busy bridge now spans it. Due to its strategic location it was the site of a prehistoric civilization and great events in two different parts of Korea's history, and has been the site of several nationalistic religious cults; therefore there are many historical relics and significant cultural sites on this beautiful island, which has led to it becoming one of South Korea's leading second-level tourist destinations. It's also one of the three counties famous for growing plenty of insam, Korea's high-quality ginseng. The northern end of the island faces Hwanghae-do problems of North Korea across the Han River estuary, and thus is heavily militarized; civilians are not permitted to visit.
Ganghwa-do contains a few dozen dolmens (prehistoric raised-up uncut boulders, mostly assumed to be tombs) from the 1st millennium BC, now registered with UNESCO (along with those in Gochang & Hwasun) as World Cultural Heritages. It was also the site of battles between Korean defenders and French and American attackers in the late 1800s, and so has several fortresses with various military relics and displays. Neither of these treasures on Ganghwa are of any interest for this website, however; they are well-covered elsewhere -- start with the official County English website.
Much more interesting for my purposes is that the Goryeo Dynasty royal court fled here for shelter from the invading Mongols in 1232, staying for 38 years, during which time the 81,000 Tripitaka Koreana printing-woodblocks (one of Korea's greatest treasures, another of its UNESCO World's Cultural Heritages, now stored at Gaya-san Haein-sa) were carved. Remains of the temporary royal palace and the Ganghwa Town Fortress around it (rebuilt many times since then) can be found, and the steep craggy mountain just west of town has come to be called Goryeo-san due to the wealth of relics and sacred sites from that era (and a fascinating Buddhist legacy from even before that) on and all around it. In addition, Mani-san in the island's southwest corner has been a site of Shamanic worship since ancient times, becoming strongly associated with the cult of Dan-gun Wanggeom, Korea's mythical founding-king -- that connection has now spread to neighboring mountains. Hyeolgu-san (just to Goryeo's south) has also become regarded as a highly-sacred mountain, and Bomun-sa Temple on another island just off the West Coast has developed into one of Korea's eight special shrines for worship of the Bodhisattva of Compassion. All together Ganghwa-do has become a very interesting place for the study of Korea's religious history and the modern revival of its indigenous spiritualism.
One theory holds that Mani-san represents Heaven, Goryeo-san represents Earth and Hyeolgu-san in between them represents Humanity -- and therefore Mani-san is the Father, Goryeo-san is the Mother and Hyeolgu-san is the Child they hold -- echoing the famous first line of the "Western Inscription" by Chang Tsai (Zhang Zai, 1020-1077, Sung Dynasty China): "Heaven (yang) is our Father; Earth (yin) is our mother; and I, this tiny thing, live comfortably enfolded in Them."
Ganghwa-do contains no less than five sacred mountains, decorated with a wide variety of wonderful cultural treasures, all forming the end of the Hannam-jeongmaek Branch of the Baekdu-daegan:
Goryeo-san (436m) (northern Ganghwa-do) (including Byeollim-san 400m & Bongcheon-san 291m) Site of several important Buddhist temples (Jeokseok-sa, Cheongryeon-sa & Baekryeon-sa) and Shamanic shrines including the large new dang of "National Shaman" [Gukmu] Kim Kum-hwa, one of Korea's most famous Manshin, and a variety of Goryeo Dynasty relics associated with various legends (including a fortress & royal tomb).
Hyeolgu-san (466m) (central Ganghwa-do) (including Toimo-san 339m) Site of several interesting Buddhist temples (Hwangryeon-sa) and Shamanic shrines, featuring a new Dan-gun Seongjeon [Saint-Hall shrine for Korea's Founding-King].
Jeongjuk-san (200m) (southern Ganghwa-do) site of Jeondeung-sa Temple
Mani-san (469m) (southern Ganghwa-do) (including Sang-bong 255m, right next on the coast) Site of the Chamseong-dan [Truly Holy Altar], an ancient stone shrine on one peak that commands a wide view of the Yellow Sea, associated with King Dan-gun. The "Demon-Expelling Mountain" also features a special shrine for Dan-gun and other national heroes, Jeongsu-sa Temple and other sites.
Sangbong-san (316m) (on Seokmo-do Island just west of Ganghwa-do). (including Haemyeong-san 309m) Site of Bomun-sa [Treasure-Gate Temple], one of Korea's eight special shrines for the Bodhisattva of Compassion (due to a carving of him on the “Eyebrow Cliff”).