Finland and Estonia undersea railway: Tunnel solution examined
Finland and Estonia have agreed to look into building an undersea railway tunnel connecting their capitals.
The tunnel - expected to cost up to 13bn euros (£10bn; $14bn) - would link up Helsinki and Tallinn, which are separated by the Baltic Sea.
Tens of thousands of Estonians commute to the Helsinki area for work, while many Finnish tourists visit Tallinn.
The railway link would reduce travel times to about 30 minutes, the city of Helsinki said.
It currently takes between 90 minutes and two hours to travel between the two cities by fast ferry.
In a statement, Helsinki officials said: "Helsinki and Tallinn together form an economic area of approximately 1.5 million people. To fully utilise the area's potential, transport between the cities should be faster and flow easier than at present."
The project is part of a wider agreement signed by the two countries on 5 January to improve transport connections.
It would form an extension to existing plans between Estonia, Latvia and Lithuania to build a Rail Baltica high-speed rail link between Tallinn and the Polish capital, Warsaw, by 2025.
Helsinki and Tallinn have been working towards the project since Estonia joined the European Union in 2004.