Tongyeong Undersea Tunnel

Beneath the narrow channel between central Tongyeong and Mireukdo Island runs a 483 m tunnel you can walk through. Completed in 1932, the Tongyeong Undersea Tunnel is regarded as the first undersea structure in East Asia, and today it carries pedestrians rather than cars. The appeal is simple: a short stroll under the seabed while boats pass overhead.

Damming the sea to dig a tunnel

Mireukdo was once a tidal island that you could reach on foot at low tide. Under Japanese colonial rule, as Japanese fishing families settled in the area, a canal was cut between town and island to shorten the journey, and the tunnel was built beneath it at the same time. Work ran from 1931 to 1932. Builders dammed the sea on both sides, drained the gap, set up formwork on the seabed and poured concrete, then removed the dams. With the canal and the tunnel built together, boats used the waterway on top while people and vehicles went underneath. Later, once Chungmugyo Bridge and Tongyeong Bridge spanned the canal, traffic moved onto the bridges and the tunnel was closed to vehicles, surviving as a walkway.

The reinforced-concrete tunnel is 483 m long, 5 m wide and 3.5 m high. Sources differ on its depth: a maximum of 10 m below sea level, or 13.5 m below the surface at high tide. Although the project was driven by the colonial authorities, it was completed with Korean labour and materials, which is why it was registered as a cultural heritage asset in 2005.

Four characters over the entrance

Above the entrance are four carved characters, 龍門達陽 (Yongmun Dalyang), usually read as "pass through the Dragon Gate and reach Sanyang", Sanyang being the district on the Mireukdo side. The calligraphy is said to be by the Japanese magistrate of Tongyeong at the time, so the inscription also stands as a reminder of the colonial period. The entrance itself has a timber truss structure.

A local tale explains why the road went under the sea instead of over it. These waters lie close to the scene of Admiral Yi Sun-sin's victory at Hansando in 1592, during the Japanese invasions, and the story goes that the Japanese would not walk across the sea where so many of their soldiers had died. It is folklore, not documented history, so treat it as such.

Tripto tips

• Access: Vehicles are banned; only pedestrians may use the tunnel, and there is no ticket.
• Time needed: Walking from end to end takes under 10 minutes; allow 20–40 minutes to look at the inscription and the information panels as well.
• Where to start: There is a tourist information booth at the Dang-dong entrance on the town side. Paved ramps lead down at both ends, and panels introducing Tongyeong's sights line the walls inside.
• Weather: Being under the sea and fully covered, the tunnel is a good walk even in the rain, handy for a wet day in Tongyeong.
• At night: Decorative lighting runs for about 1 km from the tunnel past Chungmugyo Bridge to Tongyeong Bridge, which makes for a pleasant evening walk.
• Nearby: On the Mireukdo side the Tongyeong Cable Car and Mireuksan are close; on the town side Gangguan Harbour, Dongpirang Village and the Samdo Sugun Tongjeyeong naval headquarters are about 10 minutes away by car.