The most important factor when choosing a mask, is that it should seal well in our face, if this does not happen no matter how good the mask is, it is not for us.
We should note that diving masks limit our peripheral vision, so choosing masks that do not limit too much our vision both horizontally and vertically is a good idea. In the next picture we see that the mask has a pointed shape in the upper and lower zone, this extends how far we can look up and down.
One feature to consider is having the ability to collapse the mask, on some models this is not possible because of the way the strap is attached to the mask.
Being able to collapse the mask we can store it in pockets or inside the boot of a fin while we transport the equipment.
If we use a mask where our nose is too big for the dimensions of the mask, our nose will be squashed which is not very comfortable when wearing the mask for long periods of time. Also the mask could press the area of the nasal septum, this is another sign that the mask does not have a good space for our nose.
If on the contrary our nose is too small for the mask, grabbing our nose to equalize may become uncomfortable.
The interior space of the mask must be as small as possible, this causes the volume changes in the mask when changing depth not be as noticeable.
Having a reduced air space may imply that the glass is closer to our eyes, this is an important factor for underwater photographers because the mask doesn’t put too much distance between the photographer and the viewfinder of the camera.
Another point to consider is that clear silicone masks tend to turn yellow as the mask you see in the next picture, if the mask was chosen for aesthetic factors may be this yellow color is not the most desired.
A plus for clear masks is when we want to photograph the face of a diver underwater, it is much easier to illuminate the eyes of a diver when it is with a transparent mask, this is the reason why it is so common to see clear masks in diving magazines.