Surface Marker Buoys (or SMB's) are incredibly versatile pieces of safety gear and ought to be part of every diver's kit. When diving in strong currents, popping up in expected places is not an uncommon mistake. Popping your SMB will make you much more visible to divemasters, who can send boats to pick you up. Also, in places with heavy boat traffic, deploying SMBs before surfacing can save your life. We've got different options here, from the simplest ones that fit into your tiniest pocket to more rugged versions that can double as lift bags.