Down Current in San Diego

[Oside Jimc]

Interesting read in today's signonsandiego:
Odd current pulls divers into deep waters

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Odd current pulls divers into deep waters
By Karen Kucher
Union-Tribune Staff Writer
11:45 a.m. July 1, 2009

Map data ©2009 Tele Atlas - Terms of UseMapSatelliteHybridTerrainLa Jolla Canyon Seven divers were suddenly swept into deeper ocean water while diving off La Jolla Shores Wednesday morning in what lifeguards are calling an unexplained ocean-current phenomenon.

The divers, who were in three groups, with a diving instructor among them, were sucked from about 30 feet below the surface to below 60 feet by the strange current around 7:30 a.m., said San Diego fire department spokesman Maurice Luque.

Luque said they were diving near underwater cliffs on the edge of the La Jolla Canyon, about a quarter-mile off the coast, when they were unexpectedly pulled into deeper water.

"They were diving near some cliffs and they had to hang on to the cliffs to keep from being swept further down," Luque said. "It lasted about 11 minutes."

The divers were all able to free themselves and make it out of the water without help from lifeguards.

Lifeguards noticed a discoloration in the water about the time the unusual current was reported and a city helicopter was sent out to fly over the water but by then it had dissipated, Luque said.

Lifeguards talked to other divers as they came out of the water Wednesday morning and none reported any unusual conditions.

"We are warning other divers there about what happened earlier today," Luque said. "They are being advised, but we are not keeping anybody out of the water."

Lifeguards and a representative from the Scripps Institute of Oceanography plan to talk with reporters at the La Jolla Shores lifeguard tower at noon to discuss the morning's event.

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Good thing they hung on, Scripps Canyon goes well below recreational depths!

 

[DandyDon]

Luque said they were diving near underwater cliffs on the edge of the La Jolla Canyon, about a quarter-mile off the coast, when they were unexpectedly pulled into deeper water.

Fairly common Cozumel experience. Been pulled of the top of a wall to 100 ft. Swim away from the wall to get out of it - ascend. Now if these were OW students, could be a problem.

No accidents here...?

 

[victor]

Given that the instinctive response is to hang on to the wall to stop going down it must be quite difficult to consciously swim away from the wall into the heart of the current.
I understand that the current is, in all probability, quite shallow, so 20 metres from the wall it should be dissipating.
Can you control your depth with by adding air and swiming up?
I suspect that given our drag the current will win and swimming across it as fast as possible is the only option.

 

[Bubbletrubble]

Fairly common Cozumel experience. Been pulled of the top of a wall to 100 ft. Swim away from the wall to get out of it - ascend. Now if these were OW students, could be a problem.

No accidents here...?

Nope. No accident here. (DandyDon, you almost sound disappointed. ) I think it qualifies as a potentially dangerous "incident," though. This strong current started suddenly and really surprised the divers in the water. To clarify, the dive site at which this occurred was La Jolla Shores (not Scripps Canyon as was mentioned in a previous post in this thread). 99% of the time there is little to no current at this site. That's why it made the news, I guess. It's interesting to note that this is the San Diego dive site where the majority of OW instruction occurs. In Cozumel, people expect to see strong currents...but not so in La Jolla.

For all those who aren't aware of the underwater topography at the dive site, the "wall" at La Jolla Shores is nothing like the wall at Scripps Canyon. The Main Wall at La Jolla Shores is 5 feet tall in some places and 15 feet tall in others at a depth of about 50-65 fsw. From shore, there is a very gradual slope westward to the wall, which generally runs parallel to the shore (at least in the vicinity of the Main Wall). The base of the wall very gently slopes down to greater depths, so I certainly wouldn't call it a drop-off. Anyone who calls the Main Wall an "underwater cliff" clearly hasn't done that dive before. Hyperbole. Plain and simple.

The six divers in the water were all very experienced. At least 3 had rather large photo rigs (DSLR + 2 strobes). Although I can't verify this, I suspect the instructor may have had the least number of dives out of all of them. FWIW, this was not a class dive; it was a fun "dawn patrol" dive (5:30 - 7:30 am). The divers reported that the current was quite strong from 30 - 80 fsw...but could also be felt in the shallows (5 - 10 fsw).

I did a night dive tonight at the same site and experienced no current whatsoever. It's interesting how conditions at a given dive site can change so dramatically within the same 24 hour period.

 

[DandyDon]

Nope. No accident here. (DandyDon, you almost sound disappointed.)

No, just thot maybe it belonged in Near Misses, but no worries.

With the general north to south current that passes by there and eddies on would suspect closer to shore, since I don't know the area, I'd kinda expect currents and maybe cross currents that can produce down currents on a wall. For you guys who who know the area to be current free, I guess it was quite a surprise. So they were hanging onto "base of the wall very gently slopes down to greater depths"?

Good thing it wasn't OW students.

 

[Seanpaul]

Just went through this experience last week with my buddy in the Red Sea - it is common there as well. Went from about 100 ft to 120 ft in a split second. Some heavy kicking and air in the BCD pulled us out but not at all a fun experience. Yes it qualifies as a near miss. It actually has taken a couple days for the reality of it to sink in. My heart was racing and adrenaline pumping. I thank my angel.

 

[Bubbletrubble]

No, just thot maybe it belonged in Near Misses, but no worries.

You're right, DD. This post probably doesn't belong in this forum. Perhaps a Mod can move it when he/she gets the chance.

With the general north to south current that passes by there and eddies on would suspect closer to shore, since I don't know the area, I'd kinda expect currents and maybe cross currents that can produce down currents on a wall. For you guys who who know the area to be current free, I guess it was quite a surprise. So they were hanging onto "base of the wall very gently slopes down to greater depths"?

Good thing it wasn't OW students.

I initially thought that such a strong current presenting itself so suddenly was a pretty rare occurrence for La Jolla Shores. According to Scripps Institute of Oceanography experts, however, these currents occur more frequently than we think...and can be much stronger than the incident in question.
Perhaps once a year someone in the dive community will report a transient, strong current moving in a westerly direction away from shore. Interestingly, the currents can be westward OR eastward in direction.

FYI, the "wall" is pretty much a dirt/rock vertical structure of the dimensions previously described. The divers spoke about working their way south along the wall and then feeling themselves reach for the wall as the current flowed against them. A couple of them described seeing a large amount of particulate in the water moving westward, with strands of kelp laid out completely horizontally at 70 fsw. One buddy pair described an underwater "swirl" (eddying current?). There was a significant southerly component to the current, too, since most ended up surfacing far south of their entry point (which is not the typical dive plan for these folks).

I have several friends who are local DMs and instructors. I can't imagine what it would be like trying to herd a bunch of newbies in conditions like that.

 

[Teamcasa]

Has anyone experienced this before?

From this: DelMarTimes.net | La Jolla diver recounts 'underwater tornado'

If not for their experience, a group of a half dozen seasoned divers might not have lived to tell the tale of an "underwater tornado" they encountered Wednesday in the waters off La Jolla Shores that nearly swept them into deep water and almost prevented them from surfacing.

"Neptune had an attitude this morning," said Virginia Hatter, one of the six divers who were doing underwater photography along a canyon wall when they were gripped by a phenomenon they'll never forget.

"It was a beautiful descent, crystal clear, gorgeous," she said. "Then about 20 minutes into it, the current pushed me into one of the other divers. I looked up and saw something I'd never seen before: It looked like an underwater tornado with sand and water swirling and coming toward us."

Hatter said visibility worsened immediately and a westerly current threatened to shoot them seaward.

"I thought, 'No way I'm staying down here,' " she said. "I'm no longer comfortable in my element, so I'm going to return home. It got my attention. I was scared."

A certified scuba instructor, Hatter had never experienced anything like this effect in 511 previous dives.

"It came on so suddenly, that was so bizarre about it," she added. "I was thinking earthquake. Is this receding for a tsunami? It was that unusual. It was really strange."

Maurice Luque, San Diego Fire-Rescue Department spokesman, said divers told officials the underwater effect occurred between 75 and 80 feet down and lasted about 11 minutes.

He said it caused group members to become separated, forcing a couple of them to have to "claw their way" back up and out of the canyon, and depositing a couple of others far away near the Shores boat launch.

"Everybody was safe," he said. "If they had been less experienced, the outcome could have been different - and more tragic."

Hatter learned later in the day that a Scripps Institution of Oceanography official surmised that what had overcome their group was a rare underwater movement, wherein a circular pattern that can come from hundreds of miles away makes its way up the coast and swirls with impressive force.

Following the incident, which occurred about 7:30 a.m., lifeguards were warning scuba divers to take extra precautions in the waters off La Jolla Shores.

 

[kelpmermaid]

Wow, that's bizarre. We just have to be prepared for the unexpected.

The only odd thing vaguely like that was witnessing an incoming cold current along the bottom at Casino Point. We could see the distortion along the edge like a thermocline rushing our way, so we held on to kelp as it blasted us (brrr...!). It looked like something out of Star Trek.

 

[Teamcasa]

... It looked like something out of Star Trek.

I've experienced those before as well, (freaky) maybe this incident was the same thing only more powerful?