I've read a probable scenario about accidents with small DSVs in the book Below(Edit) the Edge of Darkness (about marine biology of bioluminescence and the tech developed by the author to film/record it):

There was a small leak in a valve, used for emergency operation IIRC and the author noticed that going down - she was still light enough to ascend but she said had she been a few hundred meters deeper, she never would have made it back up due to the extra weight.

You don’t think the host ship they depart from has an emergency vessel ?

Eh, here's a question from the bbc article in question:

The vessel weighs 10,432 kg (23,000 lbs) and, according to the website, can reach depths of up to 4,000m and has 96 hours of life support available for a crew of five.

The BBC article says the sub usually dives with a 4 day supply of oxygen.

It reads like there are no tourists on this trip, just crew. Or the firm is cruel in only caring about retrieving the crew.

It reads like this 'tragedy' is marketing to other people that have a quarter million dollars for a submarine ride.

Jesus Christ, in reading about this, I had been imagining a sleek, high-tech marvel of engineering.

That thing is a slapped-together mess.

Just being bolted into that thing is nightmare fuel.

Looks like I can't watch that from Canada :(

A Titanic tourist sub. There really was a niche sub for everything.

Makes my skin crawl even thinking of having problems in a submersible.

I do hope everything is ok.

first time was the time the titanic sank? hahha

I feel like a terrible human. I thought exactly the same, and had already scrolled on past. My short-term memory loop made me scroll back up a couple seconds later.

Yep, I thought it was another maliciously compliant reddit sub 'going missing' instead of private.

The iceberg tasted blood 100 years ago, and it wasn't satisfied. It is a cold-blooded killer.

They are also playing Nearer, My God, to thee

Unfortunately, they have only kazoos due to space constraints. Frankly not what you want to hear in what might be your final moments.

Would it make you feel any better if I told you that's probably not a threat for much longer? I'm not a scientist, but my understanding is that spot is probably at a gentle simmer by now.

TBF I don't think they planned on seeing an iceberg that far south either.

I think if the sub was destroyed, it was definitely quick for them.

Its a custom built sub, the guy used parts from RV world and steers it with a Logitech pc controller.

I mean no disrespect to the dead and all, but this has the same vibes as those rich idiots plugging up Mt Everest with their corpses.