European route E20 is a part of the United Nations International E-road network. It runs roughly west–east through Ireland, the United Kingdom, Denmark, Sweden, Estonia, and Russia. Its length is 1,880 km (1,170 mi) but it is not continuous; at three points, a sea crossing is required. Roll-on/roll-off ferries make the crossings from Dublin to Liverpool and from Stockholm to Tallinn. No publicly accessible ferries traverse the North Sea from Kingston-upon-Hull to Esbjerg (as of 2019), but a ferry for commercial drivers leaves Immingham for Esbjerg on most days. From Wikipedia
