What does this number measure?
The Seine rises on the Langres Plateau, flows through Paris and Rouen among other places, then reaches the English Channel between the Le Havre and Honfleur areas. The value of 777 km is a rounded reference; different descriptions of its course give slightly different values.
This length follows the course adopted by the catalogue. Maps show simplified, sometimes partial courses; an independent bar represents the documented length, distinct from straight-line distance.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
About 775 to 777 km depending on references and measurement conventions; this reference does not claim to fix a length to the nearest metre.
Top view of a simplified geographic course of Seine, based on the available mapped segments. The reference drawing may be partial, and river systems may combine several branches. River width and the textures of water and banks are interpreted; this is not a satellite photograph. Only the lower bar represents the documented reference length; the width of the map above does not measure that length. Course data: Natural Earth, public domain. License: Public domain.