Great Lakes Earth

[Jdailey]

Since your Great Lakes Earth is quite similar to the real Earth, I would suggest you to start with a simple outline of real Earth's coasts. An atlas as reference would help a lot your work. Then you could start modifying the coasts as per your written World's description.
When you'll be satisfied with the Great Lakes Earth's coasts, you can pass to outline mountains and volcanoes, and so on.

Little by little, you'll be surprised that you'll have in front of you a good world map. You bet!

Is there some interactive website where I can do just that?

[AzurePlanet]

Is there some interactive website where I can do just that?

You could have a look at "Google My Maps".
If you sign in, you can draw points, lines, and shapes over an Earth's background.
Your maps are stored on Google Drive, then you can print them or save them as pdf, images or kml/kmz files.

Here is an example I made for you: I drew that reddish coast line of Mediterranean Sea.

Mappa di prova Linee costiere.jpg

[Jdailey]

There once was an article that can give me the power to see what the world might've looked if I raised the sea level, but for some reason, floodmaps.com is no longer open.

[AzurePlanet]

...for some reason, floodmaps.com is no longer open.

Don't worry. You can do it youself.

There's a wonderful free software called "Wilbur" which can be used to make such things and lots more.

1. You can download Wilbur here. And Wilbur tutorials too from the Tutorials Forum.
2. You can grab those Earth heightfields suggested by johnvanvliet.
3. You can get much better results than the following mine.

GLE North America.jpg GL Africa.jpg

[Jdailey]

Can this be accomplished via Photoshop? Also, which one's johnvanvliet?

[Jdailey]

Turns out that Wilbur works only on Windows, which I don't have.