I dive with a snorkel on all my OW dives. I like the added safety of having one available if a long surface swim is required, as I like to be able to look at my underwater surroundings. I use one of the dry snorkels with the hard plastic tubes, but as I understand the added drag that such snorkels cause when attached to your mask, I use a small nylon cable tie to make a "ring" around the tube, below the upper mushroom drain valve. When not in use, the snorkel is attached to my BC via a D-ring. I leave the snorkel-keep attached to my mask strap, so I only need to snap it into place for use.