From the article linked below. It seems to be as what I assumed. They knew some myths and when got intoxicated – it often happenes below 40. This is why 40 is maximum limit for recreational diving. Below 40 even oxygen starts to be toxic. But nitrogen affects so fast that on 32 we have according to general standards ca. less than minute no dec time. But o 33 half of that. Close to 40 we encounter in fact decompression dive – so no mater how long you breathe 20 seconds or 1 minute or more. If you reached 40. If do not experience nitrogen narcosis so it’s OK. But you need to have enough air to continue, then ascend to 30 and stay couple of minutes then move slowly to ca. 18. Then you need to realize you are ca. at that point. Then you can climb up using eg. mooring chain. Not faster than 18 meter for every 3 minutes. But! During every decompression dive you need to stay at ca. 5 meters for at least 3 minutes. In fact if you dive with a computer it can show you to stay longer. So at 40 your air in tank is less than 1/4 immediately. You need to calculate enough reserve for ascending. Let’s take into account it was 1982. People, especially in Russia did not know anything about diving. I mean submarines were operating since second world war. But diving in military especially in East Block was something they called „for dummies”, suicide squad. I really do not want to tell scary stories but they here begin. And I can hurt even my OWD instructor as he went through this shit.
My opinion is: something happened. But that they were not prepared for that dive. Not fit. Something made them scared that used twice as much as could of their air. Then realized that have not enough to acend normally with decompression, so decided to get back at whole risk. In 1982 people knew about problems with nitrogen. First doctor who elaborated decompression tables did it at the beginning of XX century. But in 1982 people did not know much about blending gasses, did not use much reserve air or did not prepare emergency plans. They knew probably whole risk so when forced they took whole the risk and some died.
From the book, John Scott Haldane first proposed decompression calculations in 1908. 
This is from the chapter Multilevel and Computer Diving from the official manual Adventures in Diving by PADI. I had to do 5 specializations from this book to get AOWD certificate.
Or it was criminal case. Someone got so much intoxicated that became dangerous. Inflated their „jackets” – I even do not know what Soviet used for buoyancy in 1982. Their suits are different than those we use. Hard to say if their suits are drysuits. They are a bit different idea. They look nice. Rubber nice taylored. I can say that they look really appealing, sexy. But are not as much useful as those we use like normally Viking, Scubapro, Aqualung or others. And in 80s hard to say what they were using. Probably mainly rubber suits.
In 1982, seven military divers were reported to have come across aliens under the waters of Baikal. Alexey Tivanenko, a doctor of history, said: 'At a depth of 50 metres, they met swimmers, around three metres tall, dressed in tight-fitting silvery suits. They did not have any scuba or other devices, just helmets on their heads.
'They received an order to catch the Ihtiander (half-boy, half-shark, from modern Russian folklore) – but they were immediately washed ashore with signs of decompression.
'They had two decompression devices, but one was broken. All seven people could not be put inside, so they put only four of them. And those three people, who were not put in the device, died on the beach.’
Tivanenko has likened the descriptions to ancient petroglyphs seen by some as being aliens visiting Earth. 'I have hundreds of drawings with these 'Sons of the Sky’,’ he told NTV.
'They are united by the fact that all of them are tall, dressed in suits, all with the helmets on their heads. And there are mechanisms used by astronauts today.’