Yes, a moving classroom would be challenging for one part of the course, but there's a whole lot you can cover before you get to actually marking a location and finding it.
We have two power point presentations (but we don't do 'death by power point
') that we use when we teach Introduction to GPS Use and/or Introduction to Geocaching. On Friday night it's all lab/classroom learning how to use geocaching.com, about CITO, Park Friendly caching, cache etiquette, trackables, different types of caches, terminology, all the tools/trick of creating a good hide, Lat/Long, UTM, permissions, and how to use the GPS as a geocaching tool and what all the screens on the gps are for. On Saturday we spend all our time outside practicing what we learned in the 'field'. That's when we split into two groups and folks actually see what a track looks like, see the satellites on their screens, go find 4 caches within walking distance of the college, hide a cache for the other group to find, etc.
The other issue would be that you won't have internet access or a lab full of computers. There are certainly work-arounds though - like putting some screen shots from the computer (as well as the GPS) on the power point presentation. You could go find a cache or two once you get to an island, but only certain islands have caches within walking distance from the terminal.
We were on a caching cruise last winter and found Antigua to be the best by far - but we did hire a driver named Leon for the day. He really likes taking geocachers around his island and said he prefers them to the usual tourists because we like to go to the out of the way places
. We have a link to him on our site if anyone is heading to Antigua! He also left us at Nelson's Dockyard for a few hours so we could explore the area and find a multi cache and then we continued on our island cache tour.
Away from the West Coast