Byeonsanbando occupies a square peninsula sticking out of Korea's west coast into the Yellow Sea, and it is the only national park in the country that protects a mountain range and a coastline together. The division is old and still used: Naebyeonsan for the hills inside, Oebyeonsan for the shore around the outside.
The inner half is small-scale and green — Uisangbong at 509m is the high point, which by Korean national park standards is barely a hill — with the Bongnaegugok valley, the Jikso waterfall and Naesosa, a temple founded in 633 whose carved lattice doors are among the most admired pieces of woodwork in Korean Buddhism.
The outer half is the reason most people come. Chaeseokgang is a sea cliff of sedimentary rock laid down in horizontal beds and then cut back by the waves, so the face reads as hundreds of thousands of stacked books. At low tide you can walk out onto the platform at its foot; at high tide it is underwater.
The west coast has enormous tidal ranges, and that shapes everything here — the mudflats, the fishing, the salt farms inland, and the fact that half the park's best sights have opening hours set by the moon.