Note that the 'Greenland coastlines 2017' layer is preferred for
Greenland.

=== Original Data Source ===
GSHHG: A Global Self-consistent, Hierarchical, High-resolution Geography Database

We present a high-resolution geography data set amalgamated from
three data bases in the public domain:

    World Vector Shorelines (WVS).
    CIA World Data Bank II (WDBII).
    Atlas of the Cryosphere (AC).

The WVS is our basis for shorelines except for Antarctica while the
WDBII is the basis for lakes, although there are instances where
differences in coastline representations necessitated adding WDBII
islands to GSHHG. The WDBII source also provides all political
borders and rivers. The addition of AC since 2.3.0 allows us to
offer two choices for Antarctica coastlines: Ice-front or Grounding
line. These are encoded as levels 5 and 6, respectively and users of
GSHHG can choose which set to use. GSHHG data have undergone
extensive processing and should be free of internal inconsistencies
such as erratic points and crossing segments. The shorelines are
constructed entirely from hierarchically arranged closed polygons. A
modified version of GSHHG is used by GMT, the Generic Mapping Tools.
Starting with version 2.2.2, GSHHG has been released under the GNU
Lesser General Public License.

Citation:
Wessel, P., and W. H. F. Smith, A Global Self-consistent,
Hierarchical, High-resolution Shoreline Database, J. Geophys.
Res., 101, 8741-8743, 1996

Citation URL:
https://www.soest.hawaii.edu/pwessel/gshhg/Wessel+Smith_1996_JGR.pdf