The mask is the single most important piece of equipment in snorkelling. If a mask fits correctly and comfortably then you will enjoy your snorkelling. However, an ill-fitting leaking mask makes the experience miserable. So it is worth spending time when choosing a mask, and here are some of the features to look out for. Masks are available in several different types of material ranging from plastic to rubber to silicone.
Silicone also has much less tendency to cause reaction to sensitive skin.
A key point to look out for are lenses of tempered or toughened glass. This is important when we consider the need to properly protect our eyes whilst ensuring a scratch resistant window to our water world. The glass faceplate may be in one piece or divided into two sections. Whichever you choose is largely at matter of preference. A few years ago, if you needed optically corrected lenses then two separate lenses were indicated, but now when individual correction lenses may be added to the mask, the single faceplate can be equally used.