The Tongyeong Undersea Tunnel is an undersea tunnel in South Korea that links the city of Tongyeong in Goseong County to Mireukdo [ko] island. The tunnel is 5 m wide by 3.5 m high and 483 m long, and is 13.5 m below the sea surface at high tide. Completed in 1932 when Korea was under Japanese rule, it was the first undersea tunnel in Asia.^[1] Before the tunnel was built Mireukdo was a tidal island, accessible on foot at low tide.^[2] Originally built for motor vehicles, the tunnel is now only used by pedestrians.^{[citation needed]}