The seven Russian sailors trapped in their submersible on the Pacific seabed at the weekend say they suffered from thirst, hunger and cold.
The men - rescued by a UK robot craft on Sunday after being stuck for 76 hours - wrote farewell messages as their air supply dwindled.
They are reported to be in satisfactory condition, recovering in hospital.
Their naval mini-sub snagged on nets and antenna cables off the Kamchatka peninsula at a depth of 190m (620ft).
During their ordeal, the crew had just a few gulps of water a day to drink and a few biscuits to eat.
They poured some of their scant water over the oxygen regeneration canisters so that they had air to breathe, Russian television reported.
According to Guardian clinic in Petropavlovsk-Kamchatsky today, the submariners gave their first interviews.
"The main thing was the lack of water. There was also a problem with oxygen, it was not critical but the body felt it was not enough," crew member Alexander Uibin said in footage broadcast on Rossiya television.
The submarine, which is only 13.4 meters (44-foot) long, was snagged by cables in 180 meters of water off Russia's remote Pacific coast on Thursday.
The unnamed official said the submariners had written farewell letters to their families several hours after their vessel became stranded, the report said.
"We understood we were trapped. We just had to wait for a decision. When they said that they've put everything into action, we lay flat and began to wait," said Gennady Volonin, a representative of the company that made the AS-28 mini-submarine who was on board with the other submariners.
The men wore thermal suits to protect themselves against temperatures of about 5C (41F) and were told to lie flat and breathe as lightly as possible during the rescue effort, officials said.
To conserve electricity, lights were turned off and contact with the surface was kept to a minimum.
First and foremost, it goes about the replacement of the French-Russian SaM146 engine with the Russian PD-8 aircraft engine