Seaview 180° GoPro Compatible Snorkel Mask- Panoramic Full Face Design. See More With Larger Viewing Area Than Traditional Masks. Prevents Gag Reflex with Tubeless Design
Highly rated, non-knock off model, usually $79.99 and this is the lowest I've seen it. Ships and sold by Woot, all colors and sizes $49.99
Pays for itself after snorkeling a few times especially with the kids -- no snorkel tubes that break off, strap stays on better, kids breath more naturally. Go Pro mount to boot.
For the paranoid, just remember to take breaks, especially if you feel short of breath; works great and we use it every week in Hawaii,
Cheap trick, re-antifog with toothpaste!