Pretty much the same as taking your space suit off outside the ISS.
It's on average 0.6% of Earth's atmospheric pressure, which as far as humans are concerned might as well be a vacuum. At deepest points, it's more like 1% but still that is as near to a vacuum as makes no difference for humans.
At body temperature then the moisture lining your lungs would boil, and your saliva would boil also - not your blood though, because it is enclosed in blood vessels. So, it wouldn't help either to have a supply of oxygen like a diver with an aqualung - that would be like trying to use an aqualung outside the ISS, you'd still die from the vacuum conditions.
It's on average 0.6% of Earth's atmospheric pressure, which as far as humans are concerned might as well be a vacuum. At deepest points, it's more like 1% but still that is as near to a vacuum as makes no difference for humans.
At body temperature then the moisture lining your lungs would boil, and your saliva would boil also - not your blood though, because it is enclosed in blood vessels. So, it wouldn't help either to have a supply of oxygen like a diver with an aqualung - that would be like trying to use an aqualung outside the ISS, you'd still die from the vacuum conditions.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.4k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0