So the fabric is waterproof. Are the seams sealed? Is the zipper waterproof? Thanks.

North Face does the same thing with their Base Camp duffels: waterproof fabric, but NOT waterproof seals (factory sealed) and zippers (the new type with rubber covers). These two improvements would make this type of duffel MUCH more water resistant (even if it doesn't make them completely waterproof). Seems like such a simple thing to change.

The zipper is mega-duty, but I don't think its water-tight by any means. I have the small and the med, and the flat bottom and the trapezoidal shape keep it up-right and easy to pack, (I'm looking at you, basecamp duffle), not to mention the fact that these things are pretty much indestructible. However, it isn't a dry-type bag by a long shot... not sure why the copy talks it up like that. Also, I don't know what they mean by 'shoulder harness'. Mine didn't come with a strap, just the top & side handles, which are also ridiculously burly. It does have sewn-in D-rings to accommodate a clip-in style shoulder strap, but I doubt you could carry this backpack-style. As for sizing, the small is carry-on legal, but still plenty big. I fit a 5/4 wetsuit, booties, gloves, books, plus clothes for a week in there no problem. I use the same bag for toting my fly fishing gear and it easily fits boots, waders, chest pack, reel bag and still has room for rain gear. All-in-all, an incredibly well-built and rock solid duffle. And at this price, a total bargain. You will probably give this to your kids (if you ever have any & can bear to part with it).