Saw weird sight underwater, seek explanation plz

[Andy Shan]

Hi guys I'm a relatively new free diver, also new to this forum. I'm self taught freediver thanks to valuable information on the Internet. I dive alone and I can hold my breath for 3 minutes(static apnea). However for safty reason and to avoid freediver blackout I'm only doing 1 minute dives to 30-40feet down crescent bay, Laguna Beach to see different marine life. I have a watch to keep track of my time and I will begin to ascend around 1 minute mark to breath, relax and dive more. I understand that diving alone is a very bad idea because anything can happen underwater, I'm prepared for most situations and also willing to accept the risks associated with this sport. I've done 150-200 1minute dives without any incident and never experienced a blackout in my life. Therefore, following my method I was able to stay alive. Please give me suggestions, anything is appreciated.

After my introduction... Now the question, I was diving in crescent bay, Laguna Beach. On the bottom of the ocean(I'd say that's about 30-35 feet down), near kelp field I saw this weird water swirling effect, it looks like when sugar or salt is mixed in water as a homogeneous mixture. ( I saw similar water effect in a cave diving clip once). Suddenly, entering that particular swirling water, the temperature dropped rapidly, I wore 3-4 mm suit with additional vest and hood when freediving. The tempature change freaked me out and I suddenly realized that the homogeneous mixture might also be poisonous or toxic. Realizing the fact that weird sudden temperature change plus possible toxic water could cause danger I had no choice but to surface immediately. My question is: has anyoneelse ever experienced something like that? Anybody know the possible cause? Is it dangerous? Sorry but I searched online for a very long time but just couldn't find anything. Any help is appreciated, thanks!

 

[landshark sa]

By the sounds of it what you saw / experienced is a thermocline.

This is tends to happen when two water bodies of distinct temperature difference meet. There are many causes, such as cold water up-welling or currents bringing together different bodies of water.

The swirling or obscuring effect you describe is the difference the way the colder denser water refracts light compared to the warmer less dense water and this creates the "glass ripple" effect where two water bodies meet.

 

[J Campbell]

It was most likely a thermocline as landshark said. The swirling water may have been an underwater "dust-devil" - you know the small tornado-like swirls you sometimes see dancing across a dirt field. - the same effect can occur when different temperature air masses or water masses met.

 

[Bill McIntyre]

Hi guys I'm a relatively new free diver, also new to this forum. I'm self taught freediver thanks to valuable information on the Internet. I dive alone and I can hold my breath for 3 minutes(static apnea). However for safty reason and to avoid freediver blackout I'm only doing 1 minute dives to 30-40feet down crescent bay, Laguna Beach to see different marine life. I have a watch to keep track of my time and I will begin to ascend around 1 minute mark to breath, relax and dive more. I understand that diving alone is a very bad idea because anything can happen underwater, I'm prepared for most situations and also willing to accept the risks associated with this sport. I've done 150-200 1minute dives without any incident and never experienced a blackout in my life. Therefore, following my method I was able to stay alive. Please give me suggestions, anything is appreciated.

I suggest a Freedive Recovery Vest. You can set time and depth limits and if either one is exceeded, the vest inflates and brings you to the surface with your face well out of the water. I wear one and don't even notice that I have it on. The latest version costs $1300. If it saves your life just once, its cheap at that price.

http://oceanicss.com

I live in San Clemente if you would like to look at mine.

 

[Andy Shan]

Thanks for all the response! Now take a look visually:

I found this clip, which has something very similar. it starts at 00:29.

Will it ever be dangerous to enter? If anybody know, please share your knowledge, thanks!

 

[japppo]

At 00:29 for maybe 1 second, it looks like a thermocline or boundary between fresh and saline water. Your description matches a thermocline. It looks like a layer that is out of focus and makes things look blurred. In lakes where there's little current, it is possible to have thermoclines with temperature changes up to 20 deg C. You certainly feel the change, even when wearing a suit...

 

[Mr. X]

I voted yes but only because everybody will die, even those who never dive at all! However, diving/spearing alone will not necessarily cause you to die, nor will your death necessary coincide with diving alone If you spearfish alone, you are less likely to be speared by another spearo (such as your dive buddy). Freediving, for depth or bottom time, alone strikes me as a bad idea though (SWB).

Yes, I too have notice sudden temperature drops sometimes while diving. I don't consider it remarkable. Shallow sandy beaches often have warmer water and water moves around, as do we. I notice cold areas in the bath sometimes!

Yes, I too have noticed off swirly patterns in the water. I figure it was just something in the water - perhaps the soapy gunk produced by some seaweeds (& used to make wetsuit lube, shower gels, MacDonalds milkshakes, etc), perhaps petrol/diesel (which usually smell & occur around boats). If you are unlucky, sewage? I supposed localized temperature differences might also cause lens effects due to different densities?

 

[go-hard]

Thermoclines have a few different effects in addition to the ptential visual point of difference you noticed. Here are a couple of videos showing the strong thermocline we usually have in a lake here in Auckland. This thermocline usually sits around 12m or 14m (there is another one at around 25m or so where the primary difference is temperature rather than the water clarity shonw in the videos).

 

[Brad]

I have been freediving alone for decades at the most remote places off the California coast. Being safe on and in the water is a matter of developing rituals and routines and sticking to them. I started swimming solo all those years ago and have been in the water once with someone else; a friend showed up from another boat and swam over... From my perspective there is nothing inherently unsafe about being solom it all depends on discipline and experience. Here is a moment from the back side of San Nicolas Island..

 

[growingupninja]

Thanks for all the response! Now take a look visually:

I found this clip, which has something very similar. it starts at 00:29.

Will it ever be dangerous to enter? If anybody know, please share your knowledge, thanks!

Sorry didn't watch the video yet but no, the thermocline is never dangerous. It varies and there may be multiple layers but in socal the thermocline is usually around 50' although with el nino we haven't had much of one.

In cave/spring diving there is sometimes a layer of hydrogen sulfide dissolved in the water. You can see it and it is extremely dangerous and caustic. The photo in my avatar was from a job I did in one such, the murk at my feet is hydrogen sulfide. It is lighter than saltwater but heavier than freshwater.

In certain coastal caves and springs there can also be a layer where fresh and salt water meet, you can see it mixing.