Strange Waters...

[kidspot]

While diving on Monday I suddenly found myself drop about 2 ft. and then a short time later suddenly rise up the same 2 ft. There were no waves, it was slack tide and I wasn't in an area with updrafts of downwellings. I was only in about 12 fsw and couldn't figure out why I was having so much trouble with bouyancy. At first I thought it might just have been a small case of vertigo as I was diving on a lot of Sudafed that day, and I got a couple reverse blocks during all the up-down during the dive. It was as if the water all of a sudden dissappeared beneath my body. After the second or third time this happened I finally figured out the issue. There were "waves" of brackish water I was passing through. I could see the approaching layer of fresh, then salt water approach and finally put the pieces together. I never did figure out why there were these "waves" of brackish water in the area as I've dove here nearly 200 times before and never encountered a layer of brackish water more than 6" thick here.

Made for an interesting day of diving though

Aloha, Tim

 

[justleesa]

rollercoaster ride, eh?

 

[Aloha Mermaid]

That sounds pretty weird. I was talking with my expert and this is what he thinks. It's been super flat lately. Maybe the brackish water is a result of springs from the sea floor. We get a lot of that at Five Caves and you can see and feel the difference from the salt water. If the water is really still it could be possible that pockets of fresh water are forming and they could get pretty large...large enough to swallow you up even. Imagine a "plume" of fresh water blowing out of the sea floor and you swim into it. If yuo weight yourelf for sea water and suddenly you are in fresh water you will be too heavy and drop. Then, you pop back into the sea water and you're neutral again. Add to that, you were shallow. Even with a thin wetsuit, you'll experience serious compression and bouyancy changes especially in shallow water. I think this is what happened to you. Kind of fun when it happens, huh?? Has it rained near there lately?

 

[kidspot]

That sounds like what happened Aloha Mermaid - thx.

btw it hasn't rained here much lately, but it was very calm and I know there are springs in the area, so it makes sense that there just wasn't enough wave action to "mix" things up like it normally would.

Aloha, Tim

 

[Shaka Doug]

Did you notice any thermal changes Tim?

 

[kidspot]

yup - very noticable. Probably close to a 4* difference.

 

[scubadrewvideo]

Sharks cove here on Oahu is notorious for that. You can even see the freshwater pockets from shore on a flat sunny day with good polarized sunglasses. Some of the caverns have fresh water in the back and you definitely feel the temp and buoyancy change. You can even remove your reg and take a drink, its pretty cool.

 

[Al Mialkovsky]

While diving on Monday I suddenly found myself drop about 2 ft. and then a short time later suddenly rise up the same 2 ft. There were no waves, it was slack tide and I wasn't in an area with updrafts of downwellings.
Aloha, Tim

Yep it happens just like this to me every time I dive drunk.

I guess we need to make changes Tim

I'm there for ya