Yay those mines are evil buggers. The other day I decided to take a peek at the minefields with the mission editor... I wish I hadn't. Many areas I had used as safe transit routes were literally full off minefields. Talk about ignorance being a bliss!
During the next patrol I was so paranoid about mines that I didn't submerge until it was dead obvious that I'd been spotted or would be spotted any moment. It wasn't really helpful either that the first patrol area was south of Bungo Suido and the second Korea Straits and Sea of Japan. Not many minefields in the... BOOOM!
Good job modders and devs