In 1982, I was part of a saturation dive team working in the N. Atlantic, where we "stored" ( living in the pressurized chamber complex ) at a gas pressure equivalent of 710 fsw. At one point during the 35-day dive, a "Telex" was "locked-in" for us to read - it was from our parent company's head office in Aberdeen. It told of a saturation diving accident in the N. Sea that had just occured, where 4 divers in saturation & one topside Tender were killed. The divers died of explosive decompression when the diving bell accidentally separated from the saturation complex. The 12 ata of system pressure vented out a 24" dia. hole in seconds, as the hatchways in the system were all open. The Telex urged us to insure that all of our interior hatches remained dogged-closed after transitting thru a hatchway. I recall looking over to see that we had every one of our hatches tied open!
I can assure you I wasn't long in de-rigging those lines & closing those hatches.
And yes, sat. divers have perished when the vessel they were working from foundered in stormy seas. There is no quick "out" of a saturation environment - it is usually a multi-day deco. process to slowly de-sat back to surface, thus the reality of having to "go down with the ship" is a fact of life that sat divers understand. Fortunately, such events are very rare, but the danger exists.
Regards,
DSD