For my live aboard trip to the Galapagos later this summer, I'm using Aqualung's 850 Travel Bag (roller duffel). It is large enough to carry gear & clothes in, has fin pockets on the side & only weighs just over 8lbs (light weight for its size). It has a retractable handle & large rollers on it & even when full, will not tip over easily. It conforms to airline size regulations for check- in luggage. While it may be a tad on the pricey side for luggage, it has a replacement warranty (if bought through a legitimate dealer) that is bar none. It will be replaced if broken or torn, even if it is the airlines that tear it up. Unfortunately, while it doesn't do a bad job, it is not entirely weather proof. Not sure that there is any roller duffel that is.