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Pre-made shapefiles

Mikko Vihtakari (Institute of Marine Research)

22 June, 2026

Source: vignettes/premade-shapefiles.Rmd
premade-shapefiles.Rmd

This document records how the pre-made shapefiles bundled with — or downloaded by — ggOceanMaps are produced, so the maps can be regenerated or adapted. The rendered maps are shown in the Premade maps article.

The low-resolution global shapefiles (dd_land, dd_rbathy) ship with the package. Higher-resolution regional sets are stored in the ggOceanMapsLargeData repository and downloaded automatically as needed.

The code below is shown for reference and is not run when this article is built. It uses the current sf/stars toolchain. Earlier versions used sp/rgeos; those packages are retired and the equivalents here are sf::st_transform() (reproject) and sf::st_make_valid() (fix geometries).

Setup

Download the source datasets (see Data sources) and point the path objects at the folders on your computer.

etopoPath <- "path/to/etopo"
NEDPath   <- "path/to/naturalearth"
gebcoPath <- "path/to/gebco"
EEAPath   <- "path/to/eea"
outPath   <- "path/to/output"

Coordinate reference systems are taken straight from shapefile_list():

arcticCRS    <- sf::st_crs(shapefile_list("Arctic")$crs)
antarcticCRS <- sf::st_crs(shapefile_list("Antarctic")$crs)
ddCRS        <- sf::st_crs(shapefile_list("Decimal")$crs)

Low-resolution global shapefiles

Decimal degrees

Bathymetry — both the binned raster shipped with the package and a continuous version:

# Binned raster bathymetry (shipped as dd_rbathy)
dd_rbathy <- raster_bathymetry(
  bathy = file.path(etopoPath, "ETOPO_2022_v1_60s_N90W180_surface.nc"),
  depths = c(50, 300, 500, 1000, 1500, 2000, 4000, 6000, 10000),
  proj.out = 4326,
  downsample = 1
)
save(dd_rbathy, file = file.path(outPath, "dd_rbathy.rda"), compress = "xz")

# Continuous raster bathymetry
dd_rbathy_cont <- raster_bathymetry(
  bathy = file.path(etopoPath, "ETOPO_2022_v1_60s_N90W180_surface.nc"),
  depths = NULL,
  proj.out = 4326,
  downsample = 1
)
save(dd_rbathy_cont, file = file.path(outPath, "dd_rbathy_cont.rda"), compress = "xz")

Land — Natural Earth land + minor islands. Natural Earth polygons require the s2 engine to be turned off while clipping:

s2_mode <- sf::sf_use_s2()
suppressMessages(sf::sf_use_s2(FALSE))
on.exit(suppressMessages(sf::sf_use_s2(s2_mode)))

world   <- sf::st_read(file.path(NEDPath, "ne_10m_land/ne_10m_land.shp"))
islands <- sf::st_read(file.path(NEDPath, "ne_10m_minor_islands/ne_10m_minor_islands.shp"))

world   <- sf::st_make_valid(rbind(world, islands))
dd_land <- clip_shapefile(world, c(-180, 180, -90, 90))
all(sf::st_is_valid(dd_land))

save(dd_land, file = file.path(outPath, "dd_land.rda"), compress = "xz")

Glaciers — Natural Earth glaciated areas + Antarctic ice shelves:

glaciers    <- sf::st_read(file.path(NEDPath, "ne_10m_glaciated_areas/ne_10m_glaciated_areas.shp"))
iceshelves  <- sf::st_read(file.path(NEDPath, "ne_10m_antarctic_ice_shelves_polys/ne_10m_antarctic_ice_shelves_polys.shp"))

glaciers   <- sf::st_make_valid(rbind(glaciers, iceshelves))
dd_glacier <- clip_shapefile(glaciers, c(-180, 180, -90, 90))
all(sf::st_is_valid(dd_glacier))

save(dd_glacier, file = file.path(outPath, "dd_glacier.rda"), compress = "xz")

Arctic stereographic

Vector and continuous bathymetry, reprojected to the Arctic CRS:

rb <- raster_bathymetry(
  bathy = file.path(etopoPath, "ETOPO_2022_v1_60s_N90W180_surface.nc"),
  depths = c(50, 300, 500, 1000, 1500, 2000, 4000, 6000, 10000),
  proj.out = arcticCRS,
  boundary = c(-180, 180, 1, 90),
  downsample = 1
)
arctic_bathy <- vector_bathymetry(rb)
save(arctic_bathy, file = file.path(outPath, "arctic_bathy.rda"), compress = "xz")

Land and glaciers — reproject the global layers with sf::st_transform() and repair geometries with sf::st_make_valid():

arctic_land <- clip_shapefile(world, c(-180, 180, 1, 90))
arctic_land <- sf::st_make_valid(sf::st_transform(arctic_land, arcticCRS))
save(arctic_land, file = file.path(outPath, "arctic_land.rda"), compress = "xz")

arctic_glacier <- clip_shapefile(glaciers, c(-180, 180, 40, 90))
arctic_glacier <- sf::st_make_valid(sf::st_transform(arctic_glacier, arcticCRS))
save(arctic_glacier, file = file.path(outPath, "arctic_glacier.rda"), compress = "xz")

Antarctic stereographic 

rb <- raster_bathymetry(
  bathy = file.path(etopoPath, "ETOPO_2022_v1_60s_N90W180_surface.nc"),
  depths = c(50, 300, 500, 1000, 1500, 2000, 4000, 6000, 10000),
  proj.out = antarcticCRS,
  boundary = c(-180, 180, -80, -30),
  downsample = 1
)
antarctic_bathy <- vector_bathymetry(rb)
save(antarctic_bathy, file = file.path(outPath, "antarctic_bathy.rda"), compress = "xz")

antarctic_land <- clip_shapefile(world, c(-180, 180, -90, -30))
antarctic_land <- sf::st_make_valid(sf::st_transform(antarctic_land, antarcticCRS))
save(antarctic_land, file = file.path(outPath, "antarctic_land.rda"), compress = "xz")

antarctic_glacier <- clip_shapefile(glaciers, c(-180, 180, -90, -30))
antarctic_glacier <- sf::st_make_valid(sf::st_transform(antarctic_glacier, antarcticCRS))
save(antarctic_glacier, file = file.path(outPath, "antarctic_glacier.rda"), compress = "xz")

High-resolution regional shapefiles (ggOceanMapsLargeData)

Europe

Download the EEA coastline from https://www.eea.europa.eu/en/datahub/datahubitem-view/af40333f-9e94-4926-a4f0-0a787f1d2b8f, unzip it, and point EEAPath at the folder.

europe_land <- sf::read_sf(file.path(EEAPath, "EEA_Coastline_20170228.shp"))
europe_land <- sf::st_make_valid(europe_land)
all(sf::st_is_valid(europe_land))

save(europe_land,
     file = file.path(outPath, "europe_land.rda"),
     compress = "xz")

Svalbard

The Svalbard land, glacier, and bathymetry layers (EPSG:32633) follow the same pattern: clip the source rasters/polygons to the Svalbard extent (shapefile_list("Svalbard")$limits), reproject with sf::st_transform(), and vector_bathymetry() the binned raster. They originate from the PlotSvalbard package.

Data sources

The data used by the package are not the property of the Institute of Marine Research nor the package author. Please cite the data sources used in any map you generate. See the data-source list for the references.