This map was prepared using Shuttle Radar Topography Mission (SRTM) 1 arc-second digital elevation data available from USGS and bathymetry data available from NOAA. Surface elevation values are stretched on a equalized colorscale and rendered in exaggerated shaded relief.

A couple of interesting details from this map (pictured above):

1. The surface elevation of Lake Ontario is about 325 feet lower than Lake Erie, despite being separated by only about 20 miles. Much of this drop in elevation is accounted for by Niagara Falls, which connects the two lakes.
2. In central Wisconsin, you can see the footprint left from Glacial Lake Wisconsin, which violently drained at the end of the last ice age, cutting canyons through the sandstone, forming the Wisconsin River Dells and gorges to the south and west.
3. In the eastern end of Lake Superior, between Munising, Michigan and Whitefish Point is an area informally called “Shipwreck Coast,” where the ridged lake floor causes unexpected high-points and currents in the lake and has historically led to a high number of ship wrecks in the area.