Slated at $10 billion, construction on the Fehmarn Belt Fixed Link could start as early as this year. At 11 miles long, the completed project will be the longest immersed tunnel in the world. It will run beneath the Baltic Sea and connect Denmark to Germany between the islands of Lolland and Fehmarn. Long in the planning, the bill finally giving the project the green light passed its first reading in the Danish Parliament this month. Construction could be completed as early as 2024.