Despite continuing efficiency improvements from the major aircraft manufacturers, the expanding demand for global air travel has resulted in growing greenhouse gas (GHG) emissions. Currently, the aviation sector, including US domestic and global international travel, make approximately 1.6 percent of global anthropogenic GHG emissions per annum. North America accounts for nearly 40 percent of the world's GHG emissions from aviation fuel use.
To sum up: a lot depends on your own stamina because island hopping means packing and unpacking, getting on and off buses and ferries. Limit your choice of islands to perhaps one or two less than you think you can manage. Maximise transport links to avoid backtracking or port-transferring and since you are traveling high season be aware that you will usually need bookings ahead at most places. It is possible to turn up on an island and not find a place to stay or have to make do with a third-rate option.
Airlines have substantial fixed and operating costs to establish and maintain air services: labor, fuel, airplanes, engines, spares and parts, IT services and networks, airport equipment, airport handling services, booking commissions, advertising, catering, training, aviation insurance and other costs. Thus all but a small percentage of the income from ticket sales is paid out to a wide variety of external providers or internal cost centers.