Some snorkel masks will make you feel tunnel-visioned. Choose a mask with wide peripheral vision so you will not miss anything going on underwater.
Purchase a no fog lens for minimum of preparation to keep them crystal clear during your underwater adventure.
Some lenses are specially designed to increase under water clarity during difficult light conditions by cutting down on glare. This feature makes a big difference in the whole snorkel experience.

The snorkel

One of the most common problems with all traditional snorkel masks is the mouthpiece. People who wish to snorkel for the first time often discover that they have difficulties breathing and some simply cannot use it because of a strong gag reflex.
However, if you choose a traditional snorkel mask make sure that the mouthpiece sits comfortable in your mouth and it should not feel like it is pulling. You can choose between an open tube, semi-dry snorkel or dry snorkel depending on personal preference. Snorkels have different sizes, many diverse mouthpieces that vary from the more rigid PVC to soft silicone and even extra wide tubes for maximum air inhalation.