One "cheat" is to partially put the periscope up in suspected mine-infested waters. Of course, it has to be daylight, and enough light coming through for you to see either the cables/chains and/or the mines themselves. Same with the anti-submarine nets. Only problem? Seeing them in time to be able to either stop, or change course enough to miss them. Don't forget also, that quite a few US boats disappeared without any corresponding IJN or IJA reports of ASW activity, which leaves only a diving mishap, circle runner, or more likely, a mine. It's best to avoid the areas, or get one of the new sonars, which is late in the war. Some WW2 subs did participate in minefield mapping...
- Go and be careful
