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by hamandcheese 1134 days ago
> Our knowledge of blue holes is limited by accessibility issues, sometimes due to opening being too small or the depths being so great, and sometimes due to limited oxygen in the water, making it dangerous to explore without specialized equipment.

I'm curious why lack of oxygen is a problem? We don't breathe water, so why should oxygen content matter?
2 comments
hkchad 1133 days ago
Not sure if it's the case here but typically a low o2 underwater environment means a high concentration of Hydrogen Sulfide. This can have corrosive effects on some scuba gear and generally makes visibility very poor. I've crossed through a H2S layer in a Mexican Cenote (fresh water on top, H2S in middle, Salt on bottom) it was only a few feet thick, it's not something I'd want to spend a lot of time in though. Even though you are on SCUBA you can still smell and taste it and it's not pleasant.
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nradov 1134 days ago
Right, any explorers would dive with their own breathing gas. The actual risk in some of those blue holes is not low oxygen but high hydrogen sulfide.
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