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Neil_UK
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Goggles do not, cannot, protect eyes from pressure. The pressure on both sides of goggles is nominally the same. With or without goggles, the eyes will be at approximately ambient pressure. The only thing that can isolate you from pressure at depth is a rigid suit, or a diving bell.

So why do people wear goggles underwater?

The main reason professional wear them is to keep a layer of air in front of the eyes, so that the eye lens is working between the correct refractive indexes and giving you normal vision. Replace that air with water and everything becomes very blurred. Basically the front face of the eye lens stops bending light, so you become extremely long-sighted.

The main reason amateurs wear them is to avoid the yuk factor of opening eyes under water, or irritation from biocides in the swimming pool.

There are multiple things that limit the depths divers can reach, but none involve the eyes.

Oxygen toxicity and nitrogen narcosis limits compressed air or nitrox sport dives to a few 10s of metres. To go deeper one needs extensive decompression time and expensive helium, and deeper still an addition of hydrogen. Regular commercial and navy dives tend not to exceed 500 m. Studies have pushed lower, but seem to run out of human tolerance in the 650 to 700 m range.

I did a short diving course, and the exam started with them throwing all the gear into the pool, mask included. The idea is that you need to be able to recover from an accident where everything is knocked off your face, and then some. So, open your eyes, swim to the bottom, locate blurry tank and take a breath, grab your blurry weight belt, locate blurry mask and put it on, breathe air into mask so now you can see properly, and it gets easier from there.

Neil_UK
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