Did you know that Chicago was once the busiest shipping port in North America? Some 1,500 shipwrecks are still sitting on the bottom of Lake Michigan. Husband and wife team, Cris Kohl and Joan Forsberg, are shipwreck divers and co-creators of books and DVDs about shipwrecks. Check out some of their photos of Chicago's shipwrecks in the image gallery below. Be sure to read the captions for more information!

The 10th annual Chicago Maritime Festival celebrates our rich maritime past this Saturday, Feb. 25 at the Chicago History Museum. Festival organizer Tom Kastle and Joan Forsberg join us on Chicago Tonight at 7:00 pm. For more information, visit the links below.