The maps below show coastlines of the eastern and southern US and also northwest Europe after a severe (and improbable) global warming sufficient to melt the icecaps. The coastlines assume that ocean levels have risen by 150 meters. These maps were inspired by a whimsical discussion in the Compuserve Science Forum inquiring whether "Waterworld" (the movie) was even remotely possible. Could severe global warming ever inundate all the land? The answer, of course, is no. The maps show that several states in the USA would be completely inundated in this extreme scenario, and several small European countries would suffer a similar fate. But the land is basically still there. Phew!
The Northeastern US:
Notice that New England is now an island separated from the rest of the country by the Hudson-Champlain Channel. Boston and New York City along with Long Island and most of New Jersey and all of Delaware are under water.
The southern US:
Florida and Louisiana are completely inundated. Salt water extends all the way to St. Louis, just as it did millions of years ago.
The Netherlands and Denmark are gone. The Alsacian inland sea is rather interesting. Paris and London are under water.
Due to popular demand, I've added a post-aquacalypse version of California. As expected, the Valley of California becomes a huge sea. Note Sutter "Island" in the north.
Needless to say, realistic levels of global warming will not change sea levels by anywhere near the amounts shown in these maps. They are just for fun.