3 Missing in deep dive incident - Mexico

[alaity47]

Just as a reference, what is the current speed at Peleliu Express when it is really ripping, yet still diveable? Or what about the strongest currents at Blue Corner (again, when possible to dive?) How do these current speeds compare to the downcurrent discussed in this thread? Thanks.

A 1-knot current is moving at about 100 ft per minute.

I dove recently in a current I couldn't fight, except by holding onto the rocky bottom. On the way up the anchor chain, we were completely horizontal. Once at the surface, I let go of the chain and started counting. It took about 12 seconds to go zipping the length of the 40' boat. So that was about 2 knots (or a little less), and I guarantee I couldn't have made any headway against it if I'd missed the boat. (A few divers did, and needed the drift line).

Oh, and we were in drysuits.

I wouldn't want to be swimming against anything stronger than that for more than about 30 seconds; it took all my energy to stand still if I let go of the bottom for a second. Slightly easier in a wetsuit, but still - ugh.

People who make posts saying things like "we were in a 10 knot current!" are just guessing, and not very accurately. 1 is plenty. 2 is a lot. 3 sounds pretty unnerving.

 

[Toyon]

This downcurrent stuff is alarming. Human nature would be to fin against it as it propels you downward, just as untrained swimmers fight a current rip. With your head above the surface looking at the beach, you have time and a solid point of reference to work with to escape it. For these divers, that buoy line would have been hard to abandon as a point of reference and security as they were being swept down into the canyon. Wouldn't leaving it have been counterintuitive? Mercy.

Out here in California we have seasonal winds called Santa Ana winds which can reach hurricane force below canyons leading out to the sea. They happen when bodies of cold dense air flow downward from Utah seeking equilibrium. As they slide downhill, they undergo compressional heating which gives us very dry, unseasonably (relative to other parts of the country) warm, dry conditions at times from October through March. Although we don't see similar velocities in water, since it is so dense compared to air, perhaps there is some degree of similarity which the submarine canyons there help to occur.

The report that some underwater site visited by the ROV driver had filled in at least a couple of hundred feet of sediments over a period of days you could count on your fingers suggests that perhaps some relationship existed between the seismic instability reported and the unusual current. Recent history records immense transfer of energy through water caused by underwater seismic activity in Asia.

This is a fascinating thread and I concur with Blades' assessment that research in this region would be most helpful. I extend my sympathy and condolences to the families who lost a loved one here.

 

[peterbj7]

So if you are wall diving and get caught in a strong down-current, do you generally swim away from the wall?

Can't speak in general but it's true there. I can imagine other circumstances where swimming sideways along the wall might be the thing to do.


On magnitude of currents, I generally reckon that you can't counter a current of more than 1/2 knot, give or take. There's a drift dive that I haven't done in the Sound of Mull, off the west coast of Scotland, where I believe currents of 3+ knots are commonplace. Perhaps a local can correct that statement. At anything like that speed you need to be very careful not to hit anything, as an impact with a rock could kill you. I well remember one drift dive in very poor visibility (maybe 10ft) where the current was honking and the only safe thing was to ascend immediately, and I believe that was less than 2 knots.

 

[BrianM]

I have done many dives in the area of Los Arcos, down to 200+ on the north wall. When I heard about this tragedy I was very surprised to hear of a down current in this area, as I have never had anything but leisurely dives here. I have seen conditions with an occasional slight surface current, but never a down current? Then after reading the reports here I see the mention of Mismaloya, which is actually on the opposite side of the arches from where the wall is located. What I'm trying to say is, the vertical wall of thousand of feet of depth is in a different location than Mismaloya. Also, Mismaloya beach is said to have numerous underwater caves and caverns and has lost a tremendous amount of beach area due to one huge u/w landslide in the recent past. I was eating lunch with Nacho on the beach and he mentioned the caves and told me the beach collapsed one day and what was once 100+ yards of beach from the buildings to the surf, was suddenly gone and only 20 yards of beach remains. I dont know any more than anyone else on here what actually happened, but if the group was diving in the area of Mismaloya and there was a collapse underwater, that could easily explain why there was a sudden down current that is no longer there weeks later.

Like everyone else, I am interested in getting more info on what happened.

 

[pakman]

I just spoke to the last ROV pilot to return from the scene and his information is unbelievable. By that, I mean hard to believe and if the information was reported by anyone else, I would say it wasn't accurate.

A representative from VideoRay went to an area where an earlier ROV pilot reported strong currents in a hole (cave like siphon) with a depth greater than 300 feet. Within 14 days, the VideoRay pilot reports no current and a sandy bottom at 200' at the SAME location. The VideoRay pilot returns to the same spot several days later and again finds no current and the bottom now at 100 feet. The oval shaped opening was approximately 6m x 13m and is apparently filling in.

woah... WT*:11:...! any seismic activity reported around there? that is just bizarre...

 

[La Ovejita Negra]

I checked with the seismic reports for the days proceeding the event, because a large chunk of beach collapsed at Villa del Palmar two days before while I was there. There as no notable seismic activity in or around Vallarta.

While an underwater collapse would make some sense regarding a down current or the funnel that Blades mentioned, I think it far more likely that the anchor holding the buoy slipped over the side of the canyon and the people holding on to the rope simply didn't notice. There was very poor viz and within seconds they could have descended without realizing it, esp. since according to my sources (who know all the parties involved) they were overweighted to begin with.

If there was a down current it was a freak thing. I've personally been diving in this spot many, many times in the last year (night diving, deep diving, etc...) and never felt any kind of current at depth. Los Arcos is the most popular training site for open water and all other trainings because of its LACK of currents. Why else would hundreds of snorkelers, divers and kayakers go there every day? There is a down current near Mismaloya, but it was known to local divers and avoided.

 

[Scubamedicjoe]

welcome to NC wreck divng when theres a strong current.

A 1-knot current is moving at about 100 ft per minute.

I dove recently in a current I couldn't fight, except by holding onto the rocky bottom. On the way up the anchor chain, we were completely horizontal. Once at the surface, I let go of the chain and started counting. It took about 12 seconds to go zipping the length of the 40' boat. So that was about 2 knots (or a little less), and I guarantee I couldn't have made any headway against it if I'd missed the boat. (A few divers did, and needed the drift line).

Oh, and we were in drysuits.

I wouldn't want to be swimming against anything stronger than that for more than about 30 seconds; it took all my energy to stand still if I let go of the bottom for a second. Slightly easier in a wetsuit, but still - ugh.

People who make posts saying things like "we were in a 10 knot current!" are just guessing, and not very accurately. 1 is plenty. 2 is a lot. 3 sounds pretty unnerving.

 

[Riger]

Hello all,

Scuub Nuub here....

Is it fair to say that most currents "operate" in a column of water, whether horizontal, vertical or diagonal and therefore any thrust parallel to the column, with or against would keep you in the current.

Thus ... perpendicular escape should be sought as a rule?

I accept that in the heat of battle, one might not think of this, but it may be prudent to make that part of any "buddy briefing".

Any thoughts ?

Regards
Riger

 

[DiverChix]

This is really sad. I also have been diving in the same sights that are mentioned and have never had any problems. I did have one dive that was aborted because a group of divers was not able to swim against the current.
I hope that one of the divers in the accident is not the Alejandro I know and have dived with many times over the years. Does anyone know if this is the same Alejandro that used to work with a local dive shop in PV?