Lightning strikes and diving

[Subcooled]

Let us assume that I am diving in sweet water and a lightning strikes the water a little farther away, say 100 feet away.
How would that affect me?
- I was diving during a thunderstorm last week. That's why I want to know.

Electricity will (probably) disperse in the water and not channel towards me by chance.
But what about the pressure wave?

 

[BoundForElsewhere]

Lightning and Fish

www.weather.gov

Probably not good if you're bobbing on the surface.

 

[Subcooled]

Lightning and Fish

www.weather.gov

Probably not good if you're bobbing on the surface.

True that, but what if I'm submerged?
Would I pass out and drown?
Pressure waves in water are nasty.

 

[Whitrzac]

I've heard anecdotally that 15-20ft under is safe. I'm sure theres been plenty of tech divers on deco that got caught in a popup storm

 

[Whitrzac]

The safest thing is to just carry a 2 iron with you

 

[broncobowsher]

I remember diving in the Bahamas and there were lightening flashes in the water. Neat to see, don't remember anything being that close, nobody was worried. Been told that the salt water conducts so good, and there is so much of it, not really anything to worry about.

As for a tech diver in the springs, I remember one story where they came up and decided to take an extra 20 minutes of deco and wait for the storm to pass before surfacing.

 

[FF / EMT]

Did a night dive last October in a thunderstorm, pretty cool.

 

[lowwall]

This would have been a perfect topic for the Mythbusters.

There is a risk of overpressure injuries from being in close proximity to a lightning strike, see

Investigating the risk of lightning's pressure blast wave

However, I suspect the underwater risk is minimal. The pressure wave is caused by the displacement of air immediately surrounding the bolt itself and the bolt dissipates very rapidly once it hits ground. In this case, ground is the surface of the body of water.

Even if a cohesive bolt could penetrate deeply into the water, the overpressure declines according to the inverse square law.

I wouldn't want to be directly under a strike at my safety stop, but 30m under should be OK. Don't go testing it on my word though.

 

[EKKsoldier622]

Saltwater acts like a Farraday cage. Electricity generally spreads along the surface as the path of least resistance

 

[lowwall]

Saltwater acts like a Farraday cage. Electricity generally spreads along the surface as the path of least resistance

Making it very difficult to get a cell signal during a dive