Cave Diving Rescue in China

[jonnybellman]

Might be of some interest to folks out there. Sounds like the second diver had quite the ordeal in an air pocket for several days.

‘First successful cave-diving rescue’ claimed in China

Two missing cave-divers have been extracted from a system in southern China after a search and rescue operation that lasted almost three days – and claimed as

divernet.com

 

[Cantclimbtom]

Interesting article but maybe I'm being daft but not sure the issue was explained. 2 divers separated from a group. But why...? Lost line (for 2 divers?) Kit/gas issues and retreated to a known pocket? what can be learned?
Good to hear they were rescued though!

 

[Fulk]

Quote:

The second diver, surnamed Zhou, was not however found until the early evening of 8 February. On the third day of the search the rescuers had expanded the search area and carried out at least 10 dives before finding Zhou in another air-pocket, this one 28m below the water surface and some 500m from the entry-point.

Well, that sounds incredible to me (not that I know much about diving and the mechanics/physiology of underwater breathing). At 28 m the pressure must be nearly 4 atm; what happens when you come up to the surface after 2 days (?) under those conditions? Do you get the bends (or worse)? And I wonder how come there was an air-pocket at 28 m big enough to enable a guy to breathe for 2 days. What did he do? Float on his back? I guess the water must have been relatively warm. At least, he wouldn't have died of thirst.

It sounds like an amazing story, and I'd love to know more details. Any ideas, Pitlamp?

 

[PeteHall]

Intriguing. One chap found in an air pocket at -16m, the other at -28m.

Glad they both got out and fascinated to know more about the cave!

 

[Pitlamp]

Sorry Fulk; I'm no nearer. But some valid points made above. Two days at -28 m must be close to saturation. It'd need a long journey back to the surface for safe decompression. Like you folks above, I'm intrigued to learn more. But delighted there was evidently a successful outcome.

 

[Benfool]

If the airbell was at -28m, then the air pressure inside would indeed need to be at 4bar (otherwise it would simply just fill up), therefore the bends would certainly be an issue. My software says that decompressing on air, it would take just over 2 days - although this could be cut in half with some O2. Since the artical says it took 2 hours to get him out, I suspect there is an error.

Also, in order for the airbell to be at 4bar, it would need to be completely sealed. How did that air get there? And how did it remain breathable for 2 days without becoming hypoxic and full of CO2.

I suspect the airbell was at normal surface level and that the diver needed to go down to -28m to escape - not that any of this makes the rescue any less increadable!

B

 

[ChrisB]

A couple more articles saying much the same - no reference to decompression.

Lost cave divers rescued after 69-hour operation

For 27-year-old Zhou Yuanpeng (pseudonym), a university researcher studying cave-dwelling fish, what began as a routine scientific expedition became a life-threatening ordeal which ultimately turned into a testament to human resilience and China's evolving cave-diving rescue capabilities.

www.chinadaily.com.cn

Two explorers rescued after missing for over 69 hours in underwater karst caves in S. China’s Guangxi - Global Times

www.globaltimes.cn

 

[Cantclimbtom]

On the subject of dive tables/computers, I wonder if it that site is an altitude dive?

 

[Steve Clark]

When I first started cave diving, I was asked by our instructor ‘Why do you want to learn to cave dive?’ Personally, I liked the idea of the technical challenge and diving in a new environment. Other folks have their own motivations or a particular project in mind.

Zsolt recounted his story of naively putting some sideways tension on the line, it pinging out of his hand, getting immediately lost and by some miracle finding an air pocket that he survived in for 6 days!

https://www.cbc.ca/amp/1.333094

(As above, the press is rarely accurate in the details.)

Delighted to report that he remains safe and well and is now a leading cave instructor himself, based in Hungary.

This does seem to happen quite a lot!

 

[Cantclimbtom]

Steve's China Daily link includes "...Plus, these caves weren't completely enclosed, allowing trapped divers to find air pockets." which confirms Benfool's comments

 

[mrodoc]

As others have said if the diver was breathing air at a pressure of 28m he would have to have undergone decompression treatment before returning to normal atmospheric pressure - and this would have taken some hours to do even with oxygen breaks. Easy to look up the length of time if anybody is interested. Then there is the issue of air quality. The airbell could have been very large in which case no problem at all over a limited time period.

 

[PeteHall]

I suspect the airbell was at normal surface level and that the diver needed to go down to -28m to escape - not that any of this makes the rescue any less increadable!

I had come to the same conclusion after a bit of thought.

Also, in order for the airbell to be at 4bar, it would need to be completely sealed. How did that air get there? And how did it remain breathable for 2 days without becoming hypoxic and full of CO2.

I have convinced myself that this is theoretically possible, having encountered a perched airbell at -8m, however for it to be breathable and remain breathable for that time seems implausible.

The cave water was described as turbulent, so it is possible that it had become quite saturated with dissolved air. If the water passed a deep loop, before ascending, then descending again, the dissolved air could bubble out as the pressure dropped on the way up, becoming trapped at the shallow point. Rather far fetched, but theoretically possible, I think.
Far more likely a reporting error.