Guarding Russia's navy secrets can be a dangerous business.
Scientists say seals are as intelligent as dogs
Diving in the dark and icy waters of the Arctic, scouring the silt for hidden mines and stalking enemy scuba divers - most would expect a nice pension at the end of such a career.
But some workers are ready to do the job for a daily bucket of fish.
Russia's navy seals are back in the fold, getting ready to patrol the Northern Fleet's harbours once again after several years of retirement, Russia's Ren TV reports.
Keeping devils at bay
The programme of sea mammals' combat training, now resumed at Russia's northern port of Murmansk, was started in Soviet times to patch a known vulnerability in harbour defences.
Experience shows that saboteur divers, sometimes dubbed "sea devils", can steal into any coastal area or seaport, wreaking havoc.
The threat is being taken seriously all around the world.
SEALS' DIVING SKILLS
Depth: Routine 200 metres, maximum 1,200 metres
Time submerged: Routine 15 min, maximum over 1 hour
Speed: Up to 25 mph
In the US, security around ports was stepped up after 11 September 2001 to prevent a possible attack by al-Qaeda scuba divers.
But conventional defences are often useless against such threats, Russian TV says.
Military divers guarding strategic facilities have sophisticated underwater guns to take on their adversaries.
The main problem is detecting the enemy without betraying your own presence.
In underwater combat, whoever attacks first, wins. Even the slightest wound could be lethal because water pressure leads to massive loss of blood in a matter of seconds.
Seals, with their keen senses and natural swimming skills, can detect the enemy early on and give a vital advantage to human divers guarding the harbour.
Aleksandr Mikhaylyuk, the head of the Murmansk oceanarium, says seals have also demonstrated their prowess at locating mines and diving equipment buried beneath a layer of silt.
A human diver would need a bulky metal detector to pull that off. But for seals, who often prey on small creatures lurking at the bottom, this comes naturally.
These skills can also be used for peaceful tasks, such as maintaining underwater oil pipelines.
For the seals, their work is nothing more than a game.
The oceanarium's coaches say seals, like dolphins, have a curious mind and enjoy performing in public. They readily interact with the audience, recognise regular guests and sometimes even copy their habits.
Expert mimic: A seal pretending to be a cat
Several seals at the oceanarium have taken to arching their backs like cats after a few visits to their pool by a small kitten.
It was not long before the coaches thought of a way to harness the seals' communication skills.
One unlikely spin-off project launched a few months ago is seal psychotherapy. It turns out that playing with seals helps children with psychological and mental problems recover from very serious illnesses.
Specialists say early results have surpassed the most optimistic expectations.
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