1. While Lake Superior is indeed a lake, it behaves more like an inland sea.

2. All of the four other Great Lakes, plus three more the size of Lake Erie, would fit inside of Lake Superior.

3. Isle Royale is a massive island surrounded by Lake Superior. Within this island are several smaller lakes. Yes, that's a lake on a lake.

4. Despite its massive size, Lake Superior is an extremely young formation by Earth's standards (only 10,000 years old).