Coast Guard divers descend 200' in minutes

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So, from -20 feet to -200 feet in a matter of minutes. I'm not a diver but that doesn't sound right, not by a long shot. I'm peripherally familiar with some aspects of diving, enough to know that most descents/ascents are quite slow in order to avoid the bends, but to descend fast enough that the guy 'on belay' can't hold onto the rope? Somethin' aint right.
Wonder if they got hooked on a descending whale or something.
The part of me that loves the supernatural woke up as I read the article and chimed in with a "Dahn dahn daaaaaa... maybe it's Cthulhu!"

I used to dive long time ago (never 200 ft - deepest was [I think] 150 ft). I think you could go down that fast OK.

Coming up that fast would be a problem (as air expands) esp if decompression was reqd.

I've never really understood the 'bubbles in your blood' situation when rising from a dive (mainly because no-one's ever told me, grrr!). Could someone please explain it to me?

air dissolves in your blood. oxygen is absorbed ok but nitrogen stays dissolved. The higher the pressure, the more gas can be dissolved.

My diving theory is 20 yrs old. There may have been changes.

When you heat water in a saucepan, you can see air forming small bubbles prior to water boiling. This is the air dissolved in water no longer able to stay in a dissolved state.

A quick reduction in pressure reduces the amount of nitrogen able to stay dissolved in the blood and it forms bubbles, exactly the same way as taking the top off a bottle of soda.

If you keep dives to less than 1 atmosphere (30 ft) there is no problem. Dive deeper, depending on how long you stay down (the longer the more gas is dissolved in blood and other tissues) then you have to "decompress" on the way up to allow the gas time to be released without forming bubbles.

The other possible problem is air expanding in your lungs. If you hold your breath on the way up, it is possible to rupture tissue in your lungs.

Deep diving also concentrates gas. Concentrated nitrogen has an effect said to be similar to narcotics (nitrogen narcosis). This is why on deep dives a mix of helium is used. The % of oxygen is also reduced as high levels of oxygen (under pressure) is toxic (oxygen poisoning).

We were told of the "matini effect" of Nitrogen Narcosis - meaning every 30 ft depth (if I recall right) was equivalent to having 1 martini. At 120 ft its like having 4 martinis. This effects your judgement, but is said not to be noticeable. At 120 ft I never noticed any effect.

Yeah you can force more gas in a liquid under pressure. Like carbonated water.
Without looking it up I guess oxygen and nitrogen have the about same soluablity in water
. But blood in a living human can store alot of oxygen in hemoglobin and can burn up
excess. I would guess you could inhale pure oxygen for a certain amount of time and get most the nitrogen out of your blood (if you had to make an emergency dive with
no decompression chamber but do not quote me on that )

Just the idea of having air bubbles appear in my blood puts me a bit off diving. I want to go scuba diving sometime, it sounds fun! I also want to go skydiving and snowboarding.

There is no risk at all if you don't go deeper than 30 ft. You can spend all day at 30 ft and not be at any risk.

Generally, if you only do one deep dive (on a single tank) per day there is no risk as you are not deep enough for long enough. The deeper you are, the more compressed the air is at that depth, so the less time your tank will last. From memory, my single tank used to last about 1 hr min at 30 ft and half hour at 60 ft, 15 - 20 min at 120 ft.

I used to have some decompression tables memorised (even though I never did a decompression dive) but now am too rusty to rely on memory.

Its a great experience.

I didn't say it COMPLETELY put me off diving, did I?

My Ultimate Experience: Skydiving many, many feet onto a mountain, where I'll board down to the bottom. Then I'd board down onto an exotic beach and then scuba dive! Unrealistic, I know, but you can always imagine, right?