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A comment on Divers Find Remains of Ancient Temple in Sunken Egyptian City. Parent comment

Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by nradov on Wednesday August 07, 2019 @05:35AM (#20633144)
Some sensitive areas have had good results with requiring tourists to dive with licensed local guides. But 45m is a little deeper than most recreational divers can safely go. To do it safely and get a reasonable bottom time takes some basic technical dive training plus double tanks with normoxic trimix, and a decompression stage. (I know many divers have gone deeper using a single tank with compressed air but if anything goes wrong it can turn deadly in seconds.)
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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by diveanon on Wednesday August 07, 2019 @06:00AM (#20633271)
My deepest dive on a single tank was 57m, and I wouldn't recommend that or try to repeat it. Down currents can be terrifying.

You're right that 45m puts of out of range of most divers, but it is definitely still a doable dive with decent divers on twins and a deco stage.

The visibility in the photo looks decent for a silty bottom, I wonder what the current is like since it is in the Nile.

I am also curious about what caused it to become submerged in 45m of water 1500 years ago.

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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by smileysteve on Wednesday August 07, 2019 @10:51AM (#20635244)
57m on a single tank would just be so short too; air goes quick at that depth, and the longer you stay down the longer you have to take getting up.
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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by diveanon on Wednesday August 07, 2019 @11:35AM (#20635664)
it was definitely not the plan.

I remember being hooked on the wall and seeing my bubbles descending behind me. That dive felt more like mountain climbing than diving.

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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by nradov on Wednesday August 07, 2019 @02:44PM (#20637620)
Some walls have vicious down currents, but if you just swim away from the wall a few meters the current will decline and you can establish positive buoyancy.
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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by diveanon on Thursday August 08, 2019 @05:49AM (#20643053)
You're right, but I wasn't willing to take that risk.

One of the divers in my group was already in a mild state of panic and I didn't want to chance them letting go of the wall and descending another 10m.

I had a plan to deal with the current, but oxygen toxicity is another thing entirely.

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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by nradov on Thursday August 08, 2019 @10:54AM (#20645125)
Oxygen toxicity isn't really a factor at that depth; you'd run out of air on a single tank before experiencing any toxicity symptoms. The immediate concerns would be narcosis and hypercapnia.
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Re:Divers Find Remains of Ancient Temple in Sunken Egyptian ... by Murdoch on Wednesday August 07, 2019 @02:12PM (#20637292)
Climate change?
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