I need to create a polygon vector that fills the space between two line vectors I have.


The black line vector represents the coastline, while the blue line vector indicates the 250m depth contour.

The idea is to create a polygon that represents the entire marine territory of the region that is under 250m depth (meaning, between the two line vectors)

  • It seems you have a small gap, at around NW corner, in your blue line vector layer. Do you wish to include the fixing process in the answer?
    – Kazuhito
    Commented Mar 8, 2018 at 11:38
  • 1
    @Kazuhito No need! I fixed the gap already! Thank you for noticing! Commented Mar 8, 2018 at 11:49
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    Then it will be simple enough. (1) Make sure you have small overlap between coastline and blue line. (Slightly extend end nodes of blue line) (2) Merge (Vector | Data Management Tools | Merge Vector Tools) (3) Polygonize (see ndawson's answer ). I see @krvrd's good answer now.
    – Kazuhito
    Commented Mar 8, 2018 at 12:14

1 Answer 1


To fill the area between two line layers you need:

  1. Merge layers through Merge shapes plugin.
  2. Then you'll must check are there gaps on the contour and fix them.
  3. Apply vector tool "Lines to polygons". (Vector -> Geometry Tools -> Lines to polygons).


  • If you have several lines and output polygons, you can also use polygon instead of lines to polygons Commented Mar 10, 2018 at 11:47

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