pressure

[scubatilo]

I wonder if someone here can tell me where total dark begins under the see (in day time of course), after how many meters approximately? Was there a diver who reached total dark in the water (if we disregard his torch), or it can not be reached because it is to deep and the pressure is to high? I need this information for a riddle of mine but I am also curious.

 

[Stirling]

I wonder if someone here can tell me where total dark begins under the see (in day time of course), after how many meters approximately? Was there a diver who reached total dark in the water (if we disregard his torch), or it can not be reached because it is to deep and the pressure is to high? I need this information for a riddle of mine but I am also curious.

There's more than one way to define "total dark" in the ocean. A human being would not be able to make out any light in any direction, no matter how clear the water, and even looking straight up toward the surface at noon, at about 850 meters. At 1000 meters, even the most light-sensitive animals cannot perceive sunlight (but there is still bioluminescence, so you won't necessarily encounter "total dark" even below that depth). The area below 1000 meters is known as the "aphotic" zone, which means "no-light" zone.

Just as a point of reference, photosynthesis ends at about 200 meters - meaning there is not enough sunlight (visible or otherwise) to support photosynthesis below that depth.

People can dive below 200 meters, but they cannot dive on SCUBA to 850 meters. I believe the current record is 313 meters.

 

[ScubaSarus]

Real good info there. I was just as curious as the poster with the question.

Thanks

 

[scubatilo]

Yes, real good info. But there's still one thing that's bugging me. You see, in my riddle there is a small object on the bottom of the sea in the aphotic zone and it has to be in "total dark". So my, well, probably silly question is (but what can I do since I don't know the answer): is there bioluminescence everywhere on the bottom in the aphotic zone?

 

[ScubaSarus]

yes

http://www.cartage.org.lb/en/themes/Sciences/Earthscience/Oceanography/OceanWater/Optics/Optics.htm

According to this link.

I like this stuff, good topic

 

[friscuba]

Been in total darkness one time at a depth of about 3-4 meters... a nasty thick red tide came in. My buddy grabbed my leg and I looked down and saw his arm, then just his hand, then nothing. Had to hold a light to my depth guage and then put the guage within 3 or 4 inches of my mask to see it. This was probably at 6 meters, the water started lighting at about 3-4 meters or so. I know that's not what you were asking for, just thought it was an interesting situation to have gone from light and 6-8 foot of viz to total darkness that fast.

I wonder if someone here can tell me where total dark begins under the see (in day time of course), after how many meters approximately? Was there a diver who reached total dark in the water (if we disregard his torch), or it can not be reached because it is to deep and the pressure is to high? I need this information for a riddle of mine but I am also curious.