How to Choose a Snorkel Mask.
Figuring out how your snorkel mask should be working is not something you should be doing when you are supposed to enjoy snorkeling. This is why it is critical to buy something that is not going to be stressful for you. The first thing you should determine is how well it fits. The purpose of the rubber area of the mask is to avoid water getting on your skin. If this part is not doing its work maybe because it is not snug, you will fatigue easily and problems like fogging and leaking cannot be ruled out. You will have to make several stops in emptying the water. Fogging reduces your visibility and this is not something you want.
If you do not want a bad quality material, choose silicone because your mask will be used for years before you have to replace it. When you have a rubber mask, expect brittle and cracking as it ages and these are occurrences you cannot live with. Also, the skirt of the mask should be wide. Given that it is wide, you will not have a lot of pressure on your skin which gives comfort but it also allows for a tight seal reducing the chances of leaking, fogging and other related issues which would call for constant stopping to adjust hence taking the fun out of the activity.
You need to keep your peripheral visibility even if you get the best mask. This will not be the case if the mask goes up to your eyes. This is why you should only get it after you have tried it on and confirmed that your eyesight is still great even when you have the mask on. While some masks give you tunnel vision, some will make you feel like you are looking at things through a picture window and this is not something you need. A wider view is great because you do not have to make a complete angle change in order to see a certain side. There is no mask that does not have the possibility of fog formation but you can get one that has a low fog. This is something worth checking on before buying your snorkel mask.
When you are underwater, your vision will be reduced, but you can have masks which come with a lens which increase your vision underwater. It is not an ability for you to see when there is no light but they make images clearer, sharper and crisper but removing some wavelengths from the light and reducing glare as well.