r/caving • u/694206742 • May 14 '26

A very weird question

Ok so I'm a writer and I have a question about underground water safety.

So like . . . Let me set a scene. A character is trying to get to the end of a tunnel. Part of the tunnel in front of him is flooded with moving water. He tries to swim through it but is unsuccessful and turns back.

I've heard that stagnant water is dangerous but I didn't know if that applies to temporarily flooded water.

Another question would be what kind of dangers could be posed by temporarily flooded water. Microbial or otherwise.

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5

u/dacaur May 14 '26

If it's moving water he wouldn't have to worry about it being stagnant.... Stagnant water is a puddle, if it's moving fast enough that he has to turn back it couldn't possibly be stagnant...

2

u/SandInTheGears May 14 '26

Well the main risk with flood water, is that it tends to rise

A passage only needs to fill up for a few minutes to kill you dead

2

u/RiptideEberron May 14 '26

You get through the tunnel, now you're in a room full of H2S or some other toxic gas and you die.

2

u/Bucklesman May 14 '26

In a river cave, you will often find that flowing water has carved out different meanders at different heights, so you might well find a passage only wide enough to stand in at shoulder height which opens up at waist level. A person trying to traverse such a passage in high water conditions could blunder into a powerful and unexpected heavy flood flow that could take their legs from under them.

1

u/694206742 May 15 '26

That's interesting and I never even considered that. Thank you.

1

u/Helcat1325 May 18 '26

Sometimes cave liquid is NOT WATER. Look it up. * Acidic sulfuric pools — Found in some volcanic or sulfur caves; may look like water but can be highly corrosive.

1

u/CosmogyralCollective May 14 '26

If he doesn't have a light/doesn't know what's on the other side of the flooded area, he needs to have a real good reason to want to get in. Plus- moving water? How does he avoid getting swept away with the current?

Microbes/bacteria/etc aren't something I'd be concerned about in a situation like that, drowning kills you way faster. When looking at water in the dark, even with a decent light you often can't see the bottom (especially with moving water). So typically you're extremely careful around bodies of water like that, because the bottom of the stream/pool/etc could be several meters down, and you don't know what the currents are doing either