up to 350 MB at one stage. now the individual files are around 100MB.

layers included:

Ink Outline
Land
Water
Mountain Relief
Altitude
Rivers/Lakes
Ice
Forest
Desert
Marsh
Wind Currents
Ocean Currents
Water Temperature
Rainfall
Air Temperature
Tectonics
Volcanoes
Seismic Activity
Continental Shelf

Future layers:
Cave systems
Rock types
Artesian basins