This database contains a selection of large lakes (and islands within) taken from the Natural Earth 1:50m map, the same data source as the (v3.0) world map. The lake boundaries are consistent with the 'world' database.
The data file is merely a character string which
specifies the name of an environment variable which contains the
base location of the binary files used by the map drawing functions.
This environment variable (
R_MAP_DATA_DIR for the datasets in the
maps package) is set at package load time if it does not
already exist. Hence setting the environment variable before loading
the package can override the default location of the binary datasets.
Natural Earth project https://www.naturalearthdata.com