We really like our High Sierra drop bottom wheeled duffle because the two compartments allow us to separate our snorkel gear from our clothes. They don't make the one we use any more, but they do have a couple of other models and they're very reasonably priced for the quality levels.
We also have an Eagle Creek "gear warrior" carry on 2 wheeled duffle that doesn't seem to be available any more and we love it--it holds a huge amount and weighs almost nothing. It's a more expensive brand but they have a variety of duffles. I like the looks of the 110L "cargo hauler" and the "no matter what" duffles.
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