Thanks for sharing this sobering story. I too think it was panic, perhaps her mask got ripped off by the current, and things went awry from there. We'll never know.
I learned to dive in fairly clear, farily fast moving rivers of east Tennessee, at 15. Admitedly not the best training ground, but I was young and stupid. Later, after college, I moved to the Palm Beach area to live because I loved diving so much. I got certified by the guy, who years later, went on to start the Agressor Fleet. Yep, I'm older than dirt, but still diving. Any dive off of Palm Beach is in the Gulf Stream, the world's largest river, which makes it a current dive. Sometimes the Gulf Stream can be ripping 4.5 knots. Sometimes 1.5 knots. Mostly between 2 and 3 knots. For what it's worth, based on a lifetime of diving, when current is present, plan the current into your dive, and plan on going with the current, never against it. Otherwise you get exhausted divers, masks pulled off, and divers get separated from each other with extreme ease - in a New York minute. When diving as a group in current, use a surface float and reel, and the person with the float is who you follow - the boss. If you do get separated, surface without delay and signal the boat. Even the best whistle can only be heard 1/2 mile or so with an engine running. A signal mirror can be seen for many miles, even when it is overcast it still gathers light and can generate a flicker that will be noticed over the water. I learned that in the jungles of Viet Nam, not from a dive instructor. I have had a life long amazement factor working in me over the dive industry not beating this into the head of every new diver. Several times while in Palau, and once off of Palm Beach, I got separated from the group by current. My bad. I surfaced, and had I not had the mirror, I would not have been found. The boat was at the edge of my horizon. The mirror is what saved me from taking a slow drift to Thailand or the Phillipines. The flicker of the mirror is all the boat could see. A diver gets swept away at least once a month in Palau. I was way outside the range of a whistle (I carry one too, but would never dive without a mirror) in each of these situations. And even with currents being a known risk, I was the only person on any dive I made that had a mirror with them. So here's what you can do if you decide to get back in th water. When "drift diving" the boat stays with the float, and the group stays with the reel. Stay with the person holding the reel, go with the current. No exceptions. No "lollygagging" or bug cathing unless the entire party stops, which is almost impossible in strong current. Any dive plan that has you swimming against the current, if current is more than 1/2 knott, is IMO, a dive you should sit out on deck. Don't do it. Always have a whistle and a mirror, every diver, every dive.
This dive sounds like the DM was "leading" the group, rather than sheperding the group from the rear, making sure no one was left behind. Leading from the front is, IMO, what young, inexperienced DMs do. I have found that the really seasoned divers - more than 1,000 dives gained over many years and many locations, and not all in one dive locale over a couple of years, are a cautious, careful, deliberate bunch. That's how the guy who started the Aggressor Fleet was when he was just a dirt poor divemaster and dive boat captain- in the rear, herding cats, somewhere along the wall down in Grand Cayman. I'm in that group of seasoned divers. It is unimaginable to me that there is not one among this group of "old salts" who haven't had some close calls and seen some divers not make it. There are no Rambos in this group. No Mike Nelsons, no John Waynes, no Prince of the Kingdom of Testosterona. And finally, the most important thing I can advise andy diver - listen to your inner voice. If you are not comfortable, get out of there and back to the boat, nice and easy like, relaxed. It's just a dive, not the unfound remaining Treasure of the Atocha.
I am so sorry this has happened. The other comments are completely accurate - the dive industry downplays and understates the risks - because it's bad for business. If you don't belive this, then you are still a low time diver. Stay safe. Have fun. Don't ignore your own judgment.
My condolences to the family.