The primary class for integrating cartopy into matplotlib is the GeoAxes, which is a subclass of a normal matplotlib Axes. The GeoAxes class adds extra functionality to an axes which is specific to drawing maps. The majority of the methods which have been specialised from the original Axes are there to add improved -expected- behaviour, but some are to work around limitations that the standard matplotlib axes treats data in a Cartesian way (most of which either have, or will be, submitted back to the matplotlib project). This class replaces the matplotlib Axes class when created with the projection keyword. For example: When a source projection is provided to one of it’s plotting methods, using the transform keyword, the standard matplotlib plot result is transformed from source coordinates to the target projection. For example: Any image “factory” added, will be asked to retrieve an image with associated metadata for a given bounding box at draw time. The advantage of this approach is that the limits of the map do not need to be known when adding the image factory, but can be deferred until everything which can effect the limits has been added. Currently an image “factory” is just an object with a image_for_domain method. Examples of image factories are cartopy.io.img_nest.NestedImageCollection and cartopy.io.image_tiles.GoogleTiles. All other keywords are passed through to the construction of the image artist. See imshow() for more details. All other keywords are passed through to the construction of the image artist. See imshow() for more details. All other keywords control line properties. These are passed through to matplotlib.collections.Collection. Keep track of the original view and data limits for the life of this context manager, optionally reverting any changes back to the original values after the manager exits. If no crs is given, the extents’ coordinate system will be assumed to be the Geodetic version of this axes’ projection. Currently, the only (and default) option is a downsampled version of the Natural Earth shaded relief raster. Source.