Pankoo Full Face Snorkel Mask, 180º Panoramic View Diving Scuba Mask Anti-Fog Anti-Leak Adjustable Head Straps Design Adults,Youth,Kids

My daughter used this mask while snorkeling on our cruise and she suffered from hypoxia (lack of oxygen). Upon further research, this appears to be fairly common with full facemask snorkels. If you don't exhale hard enough, you end up re-breathing the air trapped inside the mask and don't bring fresh air in.Luckily her symptoms included a severe headache, which prompted her to take the mask off. I say luckily because every person can experience different symptoms and some can be very subtle. If you don't get oxygen levels up quickly, hypoxia leads to death (look up pilots + hypoxia).Her headache went away fairly quickly and she was totally fine within 30 minutes, but it pretty much ruined her day of snorkeling at BVI.

Don't use this. There have been many recorded cases of people dying will using this to snorkel because of how it goes on your head