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Can anyone here explain why the water in the Caribbean has that incredible crystalline transparency? Everywhere else I have been on the ocean it has been murky to one degree or another - nowhere else was it like the water in a swimming pool.

I'm curious about the natural processes that make the water there so unique.
 

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Uh, it is clean.....

lots of marine life, lots of flushing water moving through and few people to totally ruin it, very few industries and sewage treatment plants to dump their stuff...

Would be nice to see more....though. 20-30' and virtually clear is an awesome sight...it does mess with your senses, as it "looks" more shallow than it is in some light, and much deeper than real in other light. Snorkeling/Scuba is a new experience in such wonderful water.
 

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Has to do with nutrients cycling from the ocean bottom to the surface. Tropical waters are warm, and warm water floats on top of the cooler bottom water, inhibiting upflow. Consequently, there is less life, nutrients, silts, etc, being circulated, which stunts the overall ability of tropical waters to sustain life. This results in water with less in it and it is therefore more transparent.

This is also why artic waters are so dense with life. With a small temperature gradient between surface and bottom, nutrients from the bottom are constantly be lifted to the surface.
 
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Also there isn't a "real" amount of soil to be washed into the water from rains and rivers.
 

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The primary reason is a lack of suspended nutrients. Not many folks pooping in the water down there. About 50 years ago I was able to scuba dive in Chesapeake Bay over the eastern shore oyster bars just south of Chesapeake Bay Bridge at Sandy Point. In early October the underwater visibility was about 12 to 20 feet and improved as winter progressed. There's a good reason that oysters tend to be fatter in Chesapeake Bay and behind Virginia's barrier islands--they have a lot of nutrients to feed upon. Oysters in the Florida Keys are really thin.

About the same time I had the privilege to dive off Guantanamo Bay at Officers Beach, which is located just outside the Naval Station anchorage. Underwater visibility there on a bad day was nearly 100 feet. The only place I found better was at Cosgrove Light off Marquesses Key, Florida. The only problem there was bull sharks, some of which measured more than 10 feet long and very aggressive. There were massive schools of huge barracuda there as well, but they tended to be more inquisitive than aggressive.

All the best,

Gary :cool:
 

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Interestingly, the island of Saba is known for it's dive industry.. when we were there the water was EXCEPTIONALLY clear, noticeably better than the 'crystal' waters of the other islands. The distance we could see underwater was unreal.

This is an island with no sand whatsoever.. so no turbidity in the local waters.
 

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Discussion Starter #7
Has to do with nutrients cycling from the ocean bottom to the surface. Tropical waters are warm, and warm water floats on top of the cooler bottom water, inhibiting upflow. Consequently, there is less life, nutrients, silts, etc, being circulated, which stunts the overall ability of tropical waters to sustain life. This results in water with less in it and it is therefore more transparent.

This is also why artic waters are so dense with life. With a small temperature gradient between surface and bottom, nutrients from the bottom are constantly be lifted to the surface.
I think you've nailed it - it has to be something a LOT more fundamental than cleanliness to achieve that kind of clarity. The water in many places here is every bit as clean or more so than in the BVI but it never achieves that crystalline "swimming pool" quality.
 

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when my parents moved to miami, inthe 50's they said the water was that clear.

some areas towards the keys are still pretty clear... not so much in miami.
 

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About 20 years ago, a crewmate of mine showed me some pictures he took in Portugal (where he lived). The boats in his pictures looked like they were floating in the air, and you could follow the rode all the way to the bottom. These weren't professional shots mind you, just snapshots from a day trip to the beach with his family.
 

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Bristol 45.5 - AiniA
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You will notice a major difference in places where there are rivers on the island bringinig in sediment. With rivers the water is dirty (not biologically so) with silt. Could see this on the north shore of Guadeloupe were a pretty big river came in - the water was not all that clear.

The clearest water is near islands with no rivers and no people. BTW, the water in Lake Ontario has become remarkably clear in the last 20 years or so as a result of zebra mussels being introduced from the ocean. They are remarkably efficient filter feeders and have removed immense amount of particulate matter. Really screwed up the native ecosystems but the water is much, much clearer - the 1000 Islands have become a significant dive site as a result.
 

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You will notice a major difference in places where there are rivers on the island bringinig in sediment. With rivers the water is dirty (not biologically so) with silt. Could see this on the north shore of Guadeloupe were a pretty big river came in - the water was not all that clear.

The clearest water is near islands with no rivers and no people. BTW, the water in Lake Ontario has become remarkably clear in the last 20 years or so as a result of zebra mussels being introduced from the ocean. They are remarkably efficient filter feeders and have removed immense amount of particulate matter. Really screwed up the native ecosystems but the water is much, much clearer - the 1000 Islands have become a significant dive site as a result.
I noticed this on a trip to Jamaica.

We flew from Negril to Montego Bay after a heavy rainfall.

It was very interesting to see how far the silt travels from the mouth of the rivers.
 

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Silt

I remembered I had this photo that shows silt from a river well. We happened to be in the San Blas Islands in Panama last year when there a period of incredible rains. So much rain over a week or so that they actually had to shut down the canal for a day - third closure in almost a hundred years. During this time of snotty weather we anchored behind a heavily-inhabited island that was across from the mouth of a river that was maybe 75' wide (we explored it with the dink before the rains came).

The water in most of the San Blas is incredibly beautiful, not so much next to this island since about 800 people poop directly into the water (they have outhouses perched over the water). Anyway, after a couple of days of heavy rain we had this huge area of brown water from the silt upstream. With the tides we would sometimes be in the brown and sometimes in the blue. The dividing line between the fresh, muddy water and the cleaner, salt water was incredible, but I guess it would gradully break down.

 

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When I was a kid out on eastern Long Island, before the LI Expressway, back when potato farms were the only thing out on the Island, I can remember the clarity of the water in LI Sound was such that you could see the bottom clearly in 20' of water. It was never Caribbean blue but crystal clear. There were also schools of porpoise which, I understand have begun to return recently after many years of the Sound being pretty polluted.

In Maine, where I've done a lot of sea kayaking, around Deer I., the water does approach that crystal blue color. I don't know why this occurs up there but the water is, again, very clean and clear. IMO it has much to do with how much man-made crap being is mixed into the water.

Lake Champlain, where I keep the boat now for the winter, is a good example of very poor water clarity because of man-made runoff and too many organic nutrients washing down from towns and farms.
 

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Bristol 45.5 - AiniA
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A physicist might be able to explain it better, but even when the water in northern and tropical locales is very clear, there is still a difference. The tropical water is more turquoise and the northern water a darker blue. I think it must be related to the angle that the sunlight is coming at.
 

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Related to the silt issue..this view of Howe Sound shows nicely the glacial till in the water from the Squamish River, and you can see how it makes its way down the fiord eventually dispersing. Also note the back eddy/upwelling of sea water in the lee of the first point.

This layer is usually only 4-6 feet deep (being fresh it's lower density and stratifies) and larger boats travelling through it will often stir up sea water in their wakes. The transition from fresh to sea water can be a drastically strong contrast line when the incoming tide meets the freshet head on.. it's quite dramatic at times.

Oddly, many people wrongly blamed the 'green/blue' water on pollution from the nearby pulp mill.

 

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Discussion Starter #16
Oddly, many people wrongly blamed the 'green/blue' water on pollution from the nearby pulp mill.

Ironically, when Woodfibre was polluting its worst, the water at the entrance to Howe Sound was very clear - you could see up to 20 feet down because everything was dead from the dioxin effluent.

Jack, have you got one of those shots that shows the Fraser runoff? That one is a real eye opener for people regarding the transport of silt by a big river.

It also explains the shoes quite well. ;)
 

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someone told me the bottom growth is a lot less in the islands. -due to lack of run off.

they said they would scrub the bottom once they crossed, and wouldn't have any growth for a few months, until they returned to the states.

-anyone?
 

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Bristol 45.5 - AiniA
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It is pretty much standard in the islands to scrub the bottom every two months or so. Perhaps less of a problem than in a nutrient-rich environment anywhere, but still a problem. At least it is nice and warm and clean to do the scrubbing. Did mine somewhere (forget where now) and I had about 20 fish hanging around to catch the little barnacles I was popping off.
 

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Charter boats don't have holding tanks; no where to empty them any way. Next time your swimming in the Bight on Norman Island remember that fact.
 

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I went scuba diving at Eleuthera (actually stayed on Harbor Island at Valentine's). One day of diving we went to Current Cut and dove "Split Reef" for our first tank. The dive master asked if I could tell how deep the water was looking down into it. I'd been in the Bahamas before and could see the sea grass growing in the bottom around the rock. You could make out the individual blades of grass. I said, very confidently, 20 to 25 feet. He smiled, said check your depth while sitting on the bottom. I did. 45 feet. I have never seen water that was "gin clear" like in the Bahamas! Oh, by the way, the ride in Current Cut is worth a trip to Eleuthera by itself. So is the Conch Chowder at Valentine's. And the pink coral sand on Harbor Island's beach...
 
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