There are a variety of snorkels available at The Scuba Doctor and it is important to recognise the difference between the styles of snorkels.
Basic snorkels are a simple tube from your mouth to the surface that allows you to breathe while your face is under the water. Snorkels with purge valves provide a way to clear your snorkel without completely surfacing.
Some snorkels have a flexible piece towards the mouth-piece of the snorkel. These are beneficial to divers as it means the snorkel hangs beside your face and not in front of your face while diving.