We think this is the best snorkel keeper available. The Apollo SV Dry Flex Snorkel Keeper is for use with the Apollo Dry Flex Silicone Snorkel, but it can also be used with other snorkels which have an elliptical tube.
This snorkel keeper features a 2 piece clip. One piece stays connected to your mask strap permanently. The second piece remains on you snorkel tube, allowing you to quickly connect and disconnect the snorkel from your mask for storage and travelling.