Jeju City tide times

Mean spring range at Jeju City is approximately 1.5 metres. The south coast (Seogwipo) has a slightly smaller range due to the ocean exposure; the east coast (Seongsan area) has similar range to the north. Haenyeo diving is timed around tidal state — the divers prefer the slack water period around low water when current is minimal and visibility is best in the inshore zone.

Seongsan Ilchulbong (UNESCO World Heritage) is a 182-metre tuff cone formed by a submarine volcanic eruption 100,000 years ago — the crater is intact and the seaward face drops vertically into the sea. The trail to the crater rim takes 20 minutes and has 25 stairs and 4 gradients. From the rim, the crater interior and the surrounding sea are visible simultaneously. 'Ilchulbong' means 'sunrise peak'; the dawn views from the rim are the classic Jeju sunrise experience. Arrive before 5:30 a.m. in summer to see sunrise and beat the crowd.

Seogwipo on the south coast is the main dive base — the warm subtropical current on the south side produces the most diverse marine life and best visibility (10 to 20 m). Popular sites include Munseom (a small islet with walls and boulders, hawksbill turtles), Seopseom, and Beomseom. The east coast (Seongsan area) has colder water with kelp forest diving and different species. Most dive operators are based in Seogwipo; the Jeju dive trip typically runs 2 boat dives per morning.

The Jeju Olle Trails are 26 official coastal walking routes totalling 437 km, encircling the island and connecting coastal villages, basalt cliffs, beaches, and wetlands. The trails were developed from 2007 and are marked with ribbon markers (the Jeju ponytail silhouette). Individual routes are 5 to 25 km; the entire island can be walked in 3 to 4 weeks. Route 1 (Siheung → Gwangchigi Beach, 15 km) and Route 10 (Hwasun → Moseulpo, 15.6 km) are consistently rated the most scenic coastal sections.

Jeju holds UNESCO's 'Triple Crown' — the only place in the world with all three UNESCO environmental designations simultaneously: Biosphere Reserve (2002), World Natural Heritage (2007, for Hallasan volcano, Seongsan Ilchulbong, and Geomunoreum lava tube system), and Global Geopark (2010). The designations recognise the outstanding volcanic geology, unique ecosystem, and cultural landscape of the island. The Jeju volcanic field is one of the most thoroughly studied shield volcano systems in East Asia.