Diving below sea level

[repodisk]

What would the effects be if you started your dive below sea level? Say if you found a cave and hiked down one mile below sea level and found a small pond that looks to be 50ft deep. And you want to dive it what are the calculations for this dive?

 

[DawgDiver]

Planning to dive hell's lake of fire are we???

 

[1_T_Submariner]

Hiked down a mile? I would be really surprised if there are caves that deep. I have never seen anyone talk about taking this into account. I'll keep watching this thread.

 

[1_T_Submariner]

Ok there are caves that deep sorry...

http://news.nationalgeographic.com/news/2004/03/0304_040304_billstonecaves.html

 

[Rainer]

Um, it's a trick question, right? All my diving is below sea level!

 

[Thalassamania]

Since you are starting out at something slightly greater than 1ata, you’d be able to dive deeper (or stay longer, there’s always that trade off) and return to the surface without decompressing. For a given exposure your decompression would also be shorter. It’s the same as diving from a shallow underwater habitat.

 

[DandyDon]

What would the effects be if you started your dive below sea level? Say if you found a cave and hiked down one mile below sea level and found a small pond that looks to be 50ft deep. And you want to dive it what are the calculations for this dive?

You'd probly die. Anyone qualified to dive a cave would know the answer, so I take it you're not. We lose a lot of divers that way. See Accidents form, run Search for "cave."

Welcome to SB. Helps to complete your profile.

 

[daniel f aleman]

I agree with Don. By asking the question you state your lack of cave dive qualifications in general - and, a mile below sea level, please. IF this is hypothetical... then none of us really know, because none of us experienced cave divers have actually made that dive.

 

[TheAvatar]

I'm no cave diver... not even a caver. I can only speculate based on altitude diving experience and training.

Diving with your surface altitude below sea level would give you a bonus safety margin if you are diving normal sea level table so long as you stayed at that sub-sea level altitude after the dive. *HOWEVER* ascent to altitude comes into play if you dive at a sub-sealevel altitude then ascend back to sea level post dive (just as if you were driving over a mountain pass or flying in a helicopter or airplane) which would possibly require a delay before ascending those 5000 or 6000 ft back to sea level depending on your end nitrogen load.

 

[jeelan]

I agree with Don. By asking the question you state your lack of cave dive qualifications in general - and, a mile below sea level, please....

actually it's a perfectly valid question which doesnt really deserve an abrupt response such as this...i believe the OP was using the cave scenario as an example only.

Diving below sea level can be done outside a cave environment too;
The Sea of Galilee on the border of Israel and Jordan is approx 210m below sea level, the Dead Sea at 400m below sea level on its shoreline and there are several more Lakes and open bodies of water that have similar characteristics.

i also agree with the previous poster that using Sea Level tables would introduce an element of safety into the dive. That being said, i'm curious whether dive computers can be set to minus altitude figures?

cheers
Jeelan