You will see under water only when you wear it, and a camera can also be attached to the top for you to take underwater pictures.
But before going for your first snorkel, you must first make yourself familiar with the different components of the mask. There are also many considerations while you are planning to buy the first one. Some of these considerations could be a matter of personal choice, while the others are obvious.
The mask you choose for diving should have strong tempered glass so that it can take in the pressure while you are below the water. When you are going down, the airspace in your mask should equalize, and so, there has to be a skirt enclosing the nose in a scuba diving mask.
Comfort and Fit vs. Color
You will find masks in all types of attractive colors, but always go for comfort. The mask’s skirt should wrap nicely around the eye area. Make sure that there are no gaps. Find a model that is a good fit, and then select from the available colors. Once you have the mask, wear it and breathe in softly through the nose. Remove your hands. See how comfortable you are, especially around the nose, temples, and the upper lip.
Colored Silicon vs. Transparent
This is a matter of personal choice. The clear silicone skirt will allow more light. Beginner divers often prefer clear masks because it gives them an open feeling and allows better peripheral vision. Underwater photographers, on the other hand, prefer opaque dark silicon as it reduces glare.
Full Face Snorkel Mask
Full face snorkel masks are better in many ways. There can be water leakages in traditional masks, limited visibility, and you may face obstructions in breathing too. You will find no such issues in full face masks. They will cost a bit more, but the additional expense is worth it.
Neoprene Strap vs. Silicon Strap
Divers usually prefer the neoprene strap as it is more comfortable. But they can slip sometimes. Go for silicon if it slips on you.
Low vs. High Volume
Volume here means how much air space you have inside your mask. A high volume mask will make you feel open and it will give you more peripheral vision. But clearing the water takes more effort. A low-profile or low volume mask will sit closer to the face and you can clear the water quickly.