An underwater tunnel is to create a high-speed rail link connecting the southern resort island of Jeju with the mainland. If the tunnel becomes a reality, it would take just two hours and 40 minutes to get from Seoul to Jeju by KTX.

A POSCO Engineering and Construction spokesman said Tuesday, "We reviewed the construction plan for the rail link and concluded that it is feasible." The builder plans to form a special team to oversee the project and has notified the government.

The rail link would involve building a 171 km railroad from Mokpo, South Jeolla Province to Jeju. Part of it would be built on a bridge and the remaining 85 km underwater.

The government conducted a feasibility study on the underwater tunnel in 2010 but put it on the back burner due to cost concerns.

But a construction industry insider said, "Since 2010 Jeju has seen a 10-percent rise in the number of tourists each year, surpassing 10 million in 2013. There is ample demand so there shouldn't be any problems in terms of financing."

A government official said, "We're looking into including the underwater tunnel in our master plan for railway infrastructure to be finalized at the end of this year."