Two divers dead in Scharendejke NLD

[Zef]

I don't think there is a halocline in Grevelingen, even at 25m, it is salt water. The Serpent is covered in tunicates, tubularia and other animals living in sea water. But to be honest, I never tasted the water at the bottom.

Besides that, a line is your own responsibility, not that of them, whoever 'they' may be.

I stand corrected on two issues:

1. The area is considered the largest saltwater lake in Europe according to wikipedia. It was an estuary that was closed off and is now considered a "lake".

2. When I started diving there 4 years ago it was explained to me the reason the bottom is so silty and devoid of life below @ 7 meters is that the saline content of the water below 7 or 8 meters is because it is fresh water....I too have never tasted the water at that depth but believe if it is not fresh water that the water at lower depths has a lower salinity than that above 7-8 meters...I have no evidence of this, it is just based on the stark contrast to the amount of life above that point to the amount below that point (fish, jelly fish, plants, etc included). The visibility is so crappy that I just assumed the rough texture of the Serpent was due to the fact that is fabricated from cement, and never noticed the tunicates and tubularia. Most of the time I have spent on the serpent I am pre-occupied with ensuring I maintain a visual of my dive partner and they maintain a visual of me. It is great place to get experience diving in a low vis scenario but in my experience the cold and the dark do not make for a pleasant or interesting dive.

Regarding the line....there was always a line there in the past over the 4 years I have dived there. I know that in some caves there are lines that are laid and maintained in place for divers to follow...of course the risk that the line may be broken/cut/etc is a risk the diver takes when following a line, but the fact that the line that was consistently present during the 4 years period prior to my last dive there was no longer present gave me reason to stay outside of the wreck as I was not prepared to run my own.

-Z

 

[Seaweed Doc]

It would be surprising to find freshwater under usually denser salt water. It can happen if freshwater entering the system is far colder than the salt water, giving it greater density. In this case, it might be a seasonal phenomenon if indeed the lower layer is fresh water at times.

 

[Miyaru]

It's not fresh water. Several decades ago a dam was placed to cut the area off the North Sea. Over time, the water became brackish and lack of currents caused bacteria growth that depleted the water of oxygen. Early 2017 a connection was opened near Bruinisse, so the tides from the Oosterschelde could refresh the water in Grevelingen lake. Another connection will be opened in the west part, goal is to have a 30cm/1ft tide difference.

 

[Diver0001]

Regarding the line....there was always a line there in the past over the 4 years I have dived there.

-Z

The line doesn't extend into the aft compartment where they were found.

I would also like to clarify something else, which is that you cannot accidentally descend into the aft compartment. You could theoretically descend into one of the forward cargo holds without initially noticing it but this is not where they were found.

The last report seems to verify what we initially thought, which is that they apparently entered the aft area under the wheelhouse without a guide line and got disoriented to the point that they were unable to find the exit.

R..

 

[Zef]

It's not fresh water. Several decades ago a dam was placed to cut the area off the North Sea. Over time, the water became brackish and lack of currents caused bacteria growth that depleted the water of oxygen. Early 2017 a connection was opened near Bruinisse, so the tides from the Oosterschelde could refresh the water in Grevelingen lake. Another connection will be opened in the west part, goal is to have a 30cm/1ft tide difference.

View attachment 465149

Hmmm....there is quite a temperature gradient there from below 7m.

 

[Rollin]

Thank you for the clarification, Diver0001. A case of misjudgement unfortunately.

Is it my impression only, or is the visibility less since the connection opened and a current stirred up the fine silt that got down the decades before? Before, I often had 10m of visibility on a clean wreck. Now, it is sometimes like diving in a mud pool.

And no, again, there is no halocline, which would mean fresh water is resting on the much heavier salt water, not the other way around.

 

[Seaweed Doc]

Hmmm....there is quite a temperature gradient there from below 7m.

Probably just a thermocline. Where I dive, you don't note them in the open ocean but you can definitely feel them in isolated bodies of water. (I've encountered them in the tropics, though, even in open sea conditions.)

 

[Tom_Ivan]

You could theoretically descend into one of the forward cargo holds without initially noticing it but this is not where they were found.
R..

Would it be possible to descend into a cargo hold then make you way into the rear while trying to find your way out?

 

[Diver0001]

Would it be possible to descend into a cargo hold then make you way into the rear while trying to find your way out?

The opening is too small to just swim in there without making a conscious choice to do so. The cargo holds are very open so getting out of them even if you are severely disoriented is a matter of ascending and swimming in any straight line, not descending and then swimming through an even smaller opening. To my way of thinking there is no way disorientation could lead a person to entering that area of the wreck by accident.

Take a look at the model I linked in post #6 of this thread. You can see the entrance of the area under the wheel house at the 2:00 mark. The honeycomb area you see at 2:04 is the area where the divers were found. I've been in that area before and I can verify that it is very dusty back there. I could easily see people getting lost in there and unable to find the exit if they weren't using a guide line.

R..

 

[Remy B.]

I struggle to understand how wreck trained and apparently experienced dives enter a wreck without a guideline.

Wreck trained is a very open title, you can get the certification on a bus, a sail boat, a single hall wreck with no to little penetration.