What is the best mask for freediving?
Because freediving includes different aspects and approaches one can use different masks with different features. Freediving in the ocean traditionally presupposes that one wishes to dive deeper than recreational snorkelling and for this a low volume mask is advised. As one dives the water pressure increases and this acts upon the air in the mask by compressing it and reducing its size. To stop the mask from sucking onto your face, you have to equalise the internal pressure to equal the outside water pressure. The freediver does this by blowing air into the mask through the nose. A mask with high volume on the surface will need a lot of air at depth to combat the water pressure. It wouldn’t be unusual for a mask to contain 25% of a diver’s lung volume.
Freedivers look for a mask with a black or coloured skirting rather than the clear or translucent. Much of a freediver’s time is spent on the surface. A clear or translucent skirt will allow sunlight to hit the inside of the lens giving an distracting reflection.
Once you have a low volume mask, the sequence is just like any mask. Establish what mask gives you are good seal and is comfortable.
Why do some freedivers use goggles?
Goggles are often used in two scenarios. There are a series of freediving disciplines that take place in swimming pools. Many freedivers use swimming goggles and nose-clips for these events to get maximum water exposure of face. The nerves in this area are very sensitive and when in contact with water trigger a stronger Mammalian Dive Reflex, thereby increasing the potential breathhold.
Goggles are used with nose-clips in the ocean for deep diving and are especially designed to be filled with water. They look just like swimming goggles but the lenses allow the diver to focus his eyesight while in the water, despite being also filled with water. In most cases these goggles are constructed with an additional lens glued inside the goggles. When a freediver is using water-filled goggles, there is no air wasted in equalising the mask so the air can all be used in equalising the ears, allowing a considerably deeper dive. With these water-filled goggles the resultant vision is not clear but it is sufficient to focus on the freediving float rope and see the tag that must be collected from the bottom plate when performing a competition dive.