For those of you wanting a purge then the Beuchat Spy Purge snorkel is a simple and efficient snorkel.  It complements the Maxlux colour masks.
Elbow snorkel with silicone tip
Simple and effective fastening system

Equipped with a drain/purge whose valve facilitates the evacuation of water.  If you get water into the snorkel simply do a hard blow and the water will exit out the purge rather than having to push the water up the shaft of the snorkel.