The criteria for defining the coastline is the line separating water from land. The EEA coastline is a product derived from two sources: EUHYDRO (https://land.copernicus.eu/imagery-in-situ/eu-hydro) and GSHHG (http://www.soest.hawaii.edu/pwessel/gshhg/) A priority defined in the input data, first EUHYDRO geometry and, as auxiliary data, GSHHG dataset. The EUHYDRO do not cover the required extension of EEA coastline. The EUHYDRO gaps are in Iceland, Canarias, Madeira, Azores, small islands (not represented in EUDEM) and the northern of Black Sea. For that reason, the GSHHG dataset is an input for the process which allow to populate the EUHYDRO shapefile.

The creation process was focused on generate the coastline as line datasets and, later, as secondary product, defining the polygon layer sea-land. Thank reiterative processes based on conversion (from water mask of EUHYDRO to polygon), selection, dissolving and conversion (to line) tools, it was possible to obtain a continuous and homogeneous coastline. The fundamental step into the workflow was the selection of sea features using the water mask polygon (with 255 value into EUHYDRO datasets). The inland water bodies (freshwaters) are rejected by these criteria, except the water bodies connected, at least by one point, to the sea (it is the cases of some transitional water bodies).

Two Baltic lagoons have been modified with the data from SVAR geodatabase version 2012_2, Swedish Meteorological and Hydrological Institute (SMHI).

The patchwork coastline has been subjected to quality assessment based on evaluate the degree of coverage and topological errors.