The Wolmi Sea Train (월미바다열차), formerly known as Wolmi Galaxy Rail, is a monorail on the island of Wolmido in Incheon, South Korea. The monorail line has 4 stations and covers 6.1 km connecting Wolmido Island to Incheon Station, the west terminus of Seoul Subway Line 1 and the Suin Line.^[1] 1.15 km is double-tracked, but the loop around Wolmido (3.94 km) is single-track. Phase 2, if built, would have added 2 km single track connecting to Dong-Incheon station, also on Metro Line 1, with a potential Phase 3 looping back to Incheon station.^[1] The system is the first in the world to use Urbanaut technology, whose selling point is an inverse T-shaped track: large wheels run on the horizontal part of the track, while small wheels press against the rail and keep it in place.^[2][3]

The project was started in 2007, where it was originally designed to be a major monorail carrying 70 passengers. The line was scheduled to open in March 2010,^[4] but opening was repeatedly postponed.^[5] The project has a poor safety record. In April 2010, a test vehicle collided with a rail inspection vehicle, causing it to crash into a station, parts of which collapsed onto the street below. In August 2010, a wheel falling from the vehicle on a test run injured a pedestrian.^[6] In May 2012, a current collector fell off the train, although there were no injuries.^[7] In 2011, Joongang Daily reported that construction had been indefinitely suspended due to "colossal corruption",^[8] and that what had been built was set to be demolished due to "safety issues".^[9] It was reported the system was not built to the specifications of the Urbanaut.^[10] A technical inspection in May 2013 revealed numerous unresolved safety issues.^[11] In August 2014, it was announced that the monorail was unsafe and the project would be abandoned.^[12]

The cost of the entire system, originally estimated at US$60 million,^[13] had risen to 110 billion South Korean won (approx. US$100 million) before construction was suspended. A revised plan in 2015 cut the size of the trains to carrying 24 passengers. Construction based on the revised plan began in February 2015 aimed to complete in Fall 2016.^[14] It was eventually opened on October 8, 2019.^[15]