It's more about function and need. Externals tend to give a lot more options in load carrying capacity but when hiking through heavy cover there bulky and have high centers of gravity. I use an external frame when carrying heavy gear into an area that does not allow other methods Like when doing trail work and carrying chain saws or hauling out an elk that I hunted.
Internal frames would more likely suit your need for traveling around the islands and and terrain you come across there. There better fit and center of gravity is better for the type of terrain you be discovering there. Get one with enough space to hold all your gear as an external 3000ci is technically bigger then a 3000ci internal so triple the holding size. Here is a link with a lot of comparisons and reviews of the top selling packs,
http://www.rei.com/category/4500001_Backpacks
Internal frames would more likely suit your need for traveling around the islands and and terrain you come across there. There better fit and center of gravity is better for the type of terrain you be discovering there. Get one with enough space to hold all your gear as an external 3000ci is technically bigger then a 3000ci internal so triple the holding size. Here is a link with a lot of comparisons and reviews of the top selling packs,
http://www.rei.com/category/4500001_Backpacks