Udo Island

Udo ("Cow Island") lies off Seongsan at the eastern tip of Jeju. Seen from the side it is said to look like a cow lying down, hence the name. The island is only about 3.8 km long with a coastline of around 17 km, yet it packs in white beaches, sheer cliffs and fields walled with black basalt, which makes it one of Jeju's most visited satellite islands.

History and island life

Signs of settlement date from 1698, and ordinary people were allowed to move here in 1840. For a long time Udo belonged to Yeonpyeong-ri in Gujwa-myeon; it became its own township, Udo-myeon, in 1986. Around 70% of the island is flat farmland known for peanuts and garlic, and haenyeo (women divers) still work the coast. With no rivers or springs, islanders once relied on rainwater for drinking.

What to see

• Seobinbaeksa (Udo rhodolith beach): the white beach on the west coast was long called a "coral beach", but it is actually made of rhodoliths, nodules of red algae that build up calcium carbonate as they roll on the seabed. About 300 m long and 15 m wide, a beach made mainly of rhodoliths is very rare, and it became a Natural Monument in 2004. Taking the nodules home is not allowed.
• Udobong (Someori Oreum): the island's highest point. From the top you see the green fields, stone walls, the lighthouse and Seongsan Ilchulbong across the water.
• Eight Views of Udo: a list drawn up by an islander in 1983. It includes Juganmyeongwol, a cave filled with moonlike light in daytime, Dongangyeonggul, a sea cave you can enter at low tide, and Jiducheongsa, the view from Udobong.
• Hagosudong Beach: a beach on the north-east side, used for swimming in summer.

Good to know

• Peanut ice cream, made with local Udo peanuts, has become the island's signature snack.
• Jeju Olle Route 1-1 circles the island. Walked without stops it takes 3–4 hours.
• Sources differ on visitor numbers: from about 1.5 million to 2 million a year.

The Eight Views in detail

The Eight Views capture how the island changes with the hour and the vantage point.

• Juganmyeongwol: a sea cave where, around 10–11 a.m., sunlight reflected off the sea throws a round, moonlike light onto the ceiling.
• Yahangeobeom: fishing boats lit up on the sea at night.
• Cheonjingwansan: Hallasan seen from Dongcheonjindong harbour, said to be the best spot to view the mountain.
• Jiducheongsa: the green panorama of the whole island from the top of Udobong.
• Jeonpomangdo: the view of Udo from Jeju itself, where it looks like a lying cow.
• Huhaeseokbyeok: a sea cliff carved with deep grooves by long erosion.
• Dongangyeonggul: a sea cave on the east coast that you can enter at low tide.
• Seobinbaeksa: the white rhodolith beach on the west coast.

Biyangdo, a tiny islet off the eastern tip, is now joined to Udo by a causeway you can walk across. With an area of about 6.18 km², Udo is the largest island in Jeju Province after Jeju itself, and it had 1,862 residents at the end of 2019. Ferries dock at two harbours: Cheonjin and Haumokdong.

How rhodoliths form

Some red algae are coralline: they lay down calcium carbonate in and around their cells. In shallow water, where waves and typhoons keep sand grains rolling, these algae grow over the grains, and after long years of tumbling they form rounded nodules. Udo's rhodoliths range from about 1 cm to 5–8 cm across and make up over 90% of the beach sediment at Seobinbaeksa. Rhodoliths are also known from places such as Florida and the Bahamas, but there they are mostly found around reefs; a beach made almost entirely of them is found nowhere else in Korea.

Getting around safely

With cars, two-wheelers, bicycles and pedestrians squeezed onto narrow island roads, accidents have been frequent: of 143 traffic accidents on Udo between 2017 and 2023, 69 involved two-wheelers. If you rent an electric trike or scooter, keep your speed down, especially on the winding lanes between fields and stone walls.

Tripto tips

• Ferries: boats leave from Seongsan Port or Jongdal Port; either crossing takes about 15 minutes. Sailings change or stop in bad weather, so check before you go.
• Getting around: buses, bicycles and rental electric mini-cars run on the island. Outside vehicles have been restricted to ease congestion; since August 2025, electric and hydrogen rental cars and charter buses with up to 16 seats are allowed. Since March 2026, unregistered low-speed rental two-wheelers, petrol rental two-wheelers and personal mobility devices are banned. Rules change often, so check ahead if you plan to bring a rental car.
• When to go: a day trip works best: in on a morning boat, out in the afternoon. Summer weekends are crowded both on the ferries and on the island's narrow roads.
• Time needed: half a day for the main sights; a full day if you want beach time and the climb up Udobong.