That's mostly because there aren't any civilian submarines worth speaking off (coke cartels don't typically go visit the Titanic).

Seriously: this is off the charts dangerous, the reputation of the operator is as good as their last dive.

I'm not sure there's any particular reason to think that this is an extraordinarily dangerous activity relative to things like mountain climbing--even on many less extreme peaks.

I don't see any reason to think why it isn't. Unless you don't have a basic understanding about the most primitive laws of physics. Even the slightest mishap at that depth and you're in more trouble than you would be if you were stranded on the ISS.

Some mountains like K2 have an extremely high kill rate and it still happens almost every year. Probably higher killing rate than all the Titanic exploration missions that did not explode in the past. It's not so much about physics but just looking at probability

I'm sure they do. But the chances of dying on board of an experimental submarine which is subjected to absolutely insane pressures are probably quite a bit higher still than the chances of dying on K2. But whether it's higher than the Titanic exploration missions is not the same as the manned Titanic missions of which there have only been very few.

Those things work right up to the moment that they do not, this stuff is at the cutting edge of technology and tourists simply have absolutely no place there. The only reason those rich folks tend to do stuff like this is because they like to brag about such stuff, not because they're interested in the science behind it (if they were they likely wouldn't go). The Titanic is less accessible than space.

> probably quite a bit higher still than the chances of dying on K2

Across history, for every 4 people who have summitted K2, 1 person has died trying.

More Darwin award candidates then. I fully support them in their choices but I find the fascination with such endeavors hard to understand. If it is a first then I get it, that's exploration and somewhat interesting. But if it is just for kicks or bragging rights then I don't get it. To me the risks don't outweigh the benefits.

You don't even need the Everests and the K2s. I won't characterize things I've done in the 6000m range or even just peaks with tricky rock sections as dangerous per se (or I probably wouldn't have done them) but people do develop serious altitude-related conditions, avalanches happen, and people just mis-step.

The particular reason is “450 atmospheres of water pressure.” This is a lot. You don’t have this type of threat to the structural integrity of your gear at Everest, etc.

It is not. The article mentions that the submarine is bolted from the outside so that even if they surface, they can’t open it from the inside. This is in the history of bad designs, the worst. We have “doors must be unlocked when the building is occupied” signs all over the country, yet, no one thought a safety hatch the can be opened from the inside in emergencies could be useful?

> no one thought a safety hatch the can be opened from the inside in emergencies could be useful?

It’s quite possible that they considered it and felt that it would compromise the structural integrity and the risk would be higher than not having it.

Then that sub should not have been designed. Because if they do surface they should be able to open the hatch.

Fair enough. I'm curious if it's uncommon on subs built for that depth, though?

Yes, very much so. There are very few of them made and most of them are ROVs not manned for very good reasons. https://en.wikipedia.org/wiki/Deep-submergence_vehicle lists about 30 of them (manned ones, there are far more ROVs), each and every one of these should be considered experimental. Typical uses are scientific exploration and navy. Tourism is definitely not a main driver behind their development.

Nuclear submarines can maintain a safe atmosphere internally with electrolytic cells and special candles, working with the wider gas management system.