There is no "just go to class" major at the academy. Even English majors will have to take 3 semesters of calc or diffe Q's, 2 semesters of chem, physics, etc. More guys probably get in to trouble there for going in to a major that they believe will be "easy" only to find out that it is not going to be a walk in the park. What they told us is to major in what interests you and that will probably be the easiest major for you. Sure Aero majors may have to take an a@# load of very difficult classes all the way through senior year, but if you have that engineering kind of mind, then it may be easier for YOU than majoring in Poli sci (although an aero major would never admitt this). And as far as oceanography is concerned... that was considered a football player major when I was there...
I think the biggest thing that gets people in trouble is when they say "I like airplanes and being an aero major will look good to the pilot selection boards." Then they realize that they arent really cut out to be an engineer. Many people struggle through, some switch majors, and some quit or get kicked out. Believe it or not I have a few friends that switched from a non-engineering major to an engineering major. All USNA midshipman have those first couple of years of calc, chem, and physics. Some guys excell and discover that they prefer numbers to words. The bottom line is it's all in the person. Unlike civillian schools, which I now have a great deal of knowledge about, there are not majors or classes that you can pass by just showing up every now and then.