A snorkeling bag is designed specifically to hold a mask, snorkel, and fins, the last of which can be pretty awkward. Snorkeling bags often have chambers intended to protect dry items from water; good ones focus on letting your wet gear drain. Dry bags, by comparison, are simply large bags designed to keep their contents dry in a single chamber. They tend to be awkward and bulky, and they don’t have a separate place for wet items. What’s more, most dry bags aren’t fully watertight. You close a dry bag by folding any extra fabric over multiple times and then securing it with a buckle or Velcro. This prevents water from dripping or leaking, but if the bag is accidentally submerged, its contents will likely get wet.In short, a dry bag may be a good item to have in your collection, but it’s not a substitute for a snorkeling bag.