You don't go to Midway Island you bloody numb nut, what you have to do is plot a course 430k North West of Midway and mark it, draw a circle of about 200 or 300 kilometres in circumference and if you're lucky you'll drop on them in there, or you might see some of their sonar lines which if you use your noggin you can plot an intercept course.
The area of battle comprised of hundreds of miles of sea so that 430 kilometres I told you to sail to is just the beginning of the area and they could be anywhere inside of that circle you've drawn, that's why you might not see them, if you play it a few times you should be able to find them every time, who knows you might even catch Nagumo having his morning cup of tea on the Bridge.
