Clearly, the more compact the mask, the less air you will need to equalize its internal pressure during the descent. As for the skirt color, they are usually either clear or black. While clear masks do allow more light in and create a less “claustrophobic” feeling, they also tend to cast images or reflections on the inside of the lens causing distractions or even loss of clarity. Black skirts, on the other hand, help to reduce glare in sunny locations. Therefore, masks with black skirts are generally better for freediving and spearfishing.
The number and color of lenses are other important considerations. As a rule of thumb, freedivers and spearfishermen choose double lens masks. Single-lens masks are usually heavier, while side-windows greatly increase the air volume of the mask. Mirrored lenses can be useful for spearfishermen, as they hide the diver’s eyes, and help to keep fish calm or even attract them to the reflection. However, they also have the darkening effect, which makes seeing into caves or in low visibility more difficult. For those divers, who want color tinted lenses, it is recommended to choose the mild tint.
When it comes to choosing the snorkel, the standard large bore J-shaped model is preferred by most freedivers and spearfishermen. The reason for this being that the snorkel has to be light and streamlined. Snorkels with dry tops and/or purge valves tend to be much bulkier or simply ineffective. They dangle, bang against your head, and create additional drag. In a nutshell, a simple open-ended contoured tube is the best for freediving.