metaldector
Contributor
I have wet suits, dry suits, and a 7mm semi-dry suit. If water enters anyone of these they are wet suits! The main difference between the semi-dry and wet suit is the addition of rubber water dams in the wrist, ankles, and neck area. While these "seals" don't keep water out they do stop water exchange so that the water heated by your body tends to remain heated rather than flushed out as in a wet suit. If I was going to dive northern waters, Great Lakes inparticular I'd dive a dry suit. The suggestion to rent before buying makes perfect sense. Lots of slightly used dry suits on the market, they may need new seals or a patch but are very servicable. Good luck in your diving, and thermal protection.