Snagged on a net at 625 feet? One day of air?
Those men are dead.
Sending down another similar craft, if there is one in the area, that doesn't have a mating hatch flange will do nothing except expose it to the same fate.
You don't know that. I remember watching a special on a similar occurrence involving Ed Link's (inventor of the Link flight simulator) submerged vessel being trapped below c. 1973. It was snagged on a cable while exploring a shipwreck (IIRC). Another craft either cut it or nudged it free. Two of the four men survived; tragically, one of the dead was Link's son.
I think we've had quite a few technological advances in 30+ years, so keep the faith. Let me see if I can dig up that story.
Prayers going out for these Russian sailors and their families.
At Link Port, Ed Link continued designing a new submersible improving on the Deep Diver design. Johnson-Sea-Link was made of an aluminum alloy and acrylics for a lighter submersible. The acrylics were used to create a huge transparent acrylic sphere to be the pilot/observer's compartment. The aluminum alloy was used for the frame to hold the diver's compartment, battery pods, and other component parts. In 1989, the Living Seas exhibit at Disney World called it "futuristic"…today. And the submersible had been in use almost 20 years!
An unfortunate accident with Johnson-Sea-Link in the early 1970s resulted in the development of a cabled observation and rescue devise (CORD). The Johnson-Sea-Link became entangled in the wreckage of an old destroyer off Florida's coast. Two divers, Albert Stover and the Link's son Clayton, died in the accident. Ed Link devoted the next two years assisting in the design of CORD that works in conjunction with a surface ship. The unmanned CORD uses television cameras, lights, and hydraulic-powered claws and cutters, that allow it to free a trapped submersible. It was one of the first remotely operated vehicles (ROVs) used.
Get a big helo or two, run the cables underneath it and lift it off the floor.
Maybe. If they have grippers/arms/manipulators/waldos (whatever the heck they're called) They might be able to cut them free.
Worth a try anyway.
Or perhaps they can grapple them loose.
If one of the ships is a mine sweeper they might be able to use the cable cutters to free them.
Too early to give up...