isn't Anna's body fat % way too high for her to be able to stay that far underwater?
Yep.
Won't she just shoot up to the surface like a cork shooting out of a champagne bottle?
Yep.
From experience, this can happen to people of any weight in salt water, if their BF% is high. A chubby, short, 140 pounder can cork to the top when their air runs down.
Is the weight of the oxygen tanks enough to keep her underwater,
Nope.
or will they have to strap weights to her feet? (
They have to give weights to pretty much everybody. Living human bodies want to float. You wear a belt, and they give you sandbag weights. Obviously everyone needs a different amount. It can change for a person day to day as your bahdy changes, and depending on how salty the water is.
The compressed air is very heavy, so it does provide a lot of weight. But then your buoyancy can change a lot as you use up your air, even if you're wearing lots of weight. The more body fat you have, the more you float.
Like everything else, scuba science was developed with men as the default, and the ideal male body had very little body fat. I'm not saying scuba would be drastically different in a matriarchal parallel dimension.
I'm just saying, the technology is built for people with 5% body fat. People with 20% body fat struggle to stay down in salt water.
I wouldn't even guess what her BF% is. 90?
If she actually finds a scuba guide, and she actually gets into the wetsuit without a heart attack or panic attack, she might actually be able to do the pool sessions. But there's no way she'll be able to maintain neutral buoyancy in natural salt water. To say nothing of an open water swim in scuba gear!
My guess is she'll settle for a snooba experience. Snooba is like snorkeling, except you're using scuba tanks that float on the surface, with a long hose to your rebreather.
You don't need any special training for snooba. It's basically the same risk level as snorkeling, which any fat idiot can do. It's awesome too, I'd recommend it to anyone. You also don't need a wetsuit, though you might want one since you can get down to chillier depths (after about 3-5 feet the water gets noticeably colder, even in very hot locales.)
You can get down to about 20 feet, which is a drastically different experience than snorkeling at the surface.
Well, the average person could get down to 20 feet. I don't think Anna could dive more than 5-10 without corking back up.