Are the classes on board high quality? Were they comparable to the classes you would take at your home university?

I really loved my Medical Anthropology and Business Ethics course. The classes were interactive and thought-provoking for me personally. I'm not sure what you would consider as "high quality" but the Professors on SAS are usually very passionate about the subject that they are teaching and can really dive into how that particular subject is applicable globally; almost all classes incorporate a little bit of each country/continent that you visit into the curriculum, which I thought was really awesome. Having an engaging professor who is happy to share their expertise with you is really the least that I look for in my POV of a high-quality class course. I also took Introduction to Psychology -- my spiel on that is that introductory or general requirement course material is pretty standard across the board (you can only really cross your fingers and hope the professor is able to make it as least dry as possible). Beyond my own experience, I had friends that took Astronomy classes taught by real life astronauts and really loved it. If you plan to attend SAS, take a look into what courses are offered and who the professors are. They are always changing but with sites like ratemyprofessor.com, I think you can get a somewhat general feel on teaching styles.
Classes are pretty hard to compare even within a university because students' interests and learning priorities vary so greatly, but if you're the type that is able to learn outside of the classroom as well as within one then I think any class taken can be considered fruitful.

As reference, I was a Senior at UC Berkeley at the time that I attended Semester at Sea.

The classes were very high quality. All of the professor are very, very qualified and truly care about the subjects being taught. It's quite different from classes at your home university due to the fact that they are all international focused and mainly revolve around the countries being visited. One thing I really liked was the fact that everything I learned was applied to a current event in which ever country was being studied. For example, in a political science course I was taking we looked at how Brazil is handling the preparation for the 2016 Summer Olympics and how the concepts from class applied to certain situations pertaining to it. All professor were able to apply the concepts being taught to real world examples which I found to be very helpful. I think that a lot of courses at home universities focus on theoretical concepts and often forget to teach them in a way that suits real world application.

The classes on Semester at Sea were a bit less challenging than my normal university classes at Boston College. However, I attribute this mainly to the fact that I attended every single class on the ship and had ample time to complete my studies. At school, I am prone to missing class and often get distracted on campus leaving less time for homework and studying. Since we only took classes while we were sailing, there was no reason not to go, i.e. no other distractions that would keep you from class. In terms of quality, I believe the classes were very high quality! I had professors from across the world and different disciplines, for example, my World Religions professor was the chair of his department at Brown University and my epidemiology teacher was from and taught in Norway. Additionally, each class requires 1 field assignment, this means that for each class you take you will have a 'field trip' in one of the countries you visit, and these are always really amazing cultural and educational experiences that you might not have chosen to plan by yourself, but that you will ultimately be grateful for attending!

The difficulty of the classes aboard the ship vary for different reasons. I went on a summer voyage which made the classes very condensed requiring a lot of work in a short time. I also was on the ship when it was controlled by UVA academics which have a higher quality of education. There are no longer summer voyages nor is UVA, I believe, no longer the school sponsoring semester at sea.
Overall, from my experience and taking to students from other voyages, academic difficulty is closely related to that of courses you would take at your home school. You have assignment, papers and exams just as you normally would. Also, like any university the level of difficulty depends on the course you take. A science or math related course is more difficult than a extra curricular course like art.

Although classes try to tie in the cultures of the countries you visit. Time aboard the ship, while not in port, is like any other school day. Minus eating lunch outside with a ocean view of course! It is definitely manageable and worth it to travel and study with semester at sea!

The classes are awesome! One class is a bigger lecture but the rest are smaller (like private university size). They are so involved and awesome because you can learn about the world while you're experiencing it! Teachers come from universities all over and they're brilliant! When you have an extra question, you can find them easily, in the hallways, dining hall, on the decks, or email always works. It's amazing how well they care about students and how easy it is to get the help you really need.
Let me know if I can help any more!

The classes were very comparable to what I experienced at my home university. I attend the University of Southern California, so my classes are quite rigorous, however my teachers on Semester at Sea were from Harvard, UNC Chapel Hill, and Wesleyan, and they used the curriculum for their classes on the ship as they would at their home universities. Each class had 2 midterms and a final and 2 papers each, which kept me busy. However, that being said, teachers were lenient with deadlines as they understood what our time off the ship entailed.