There are ten (10) base map options: Topographic, Satellite, Terrain, Hybrid, Disturbance, EVT, FM, EVC, EVH, and BPS. The first 4 of these are map services from ESRI.
The topographic basemap includes boundaries, cities, water features, physiographic features, parks, landmarks, transportation, and buildings.
The satellite basemap presents high resolution imagery for the the United States.
The terrain basemap features shaded relief imagery, bathymetry, and coastal water features.
The hybrid basemap is a a blend of satellite and high-resolution aerial imagery with political boundaries, roads, and some labels.
Six of the base maps are based on the LANDFIRE spatial data products from 2012: Disturbance, EVT, FM, EVC, EVH and BPS.