Russians Claim Deepest Dive...

... in a freshwater lake. I know, its not the deep sea but it is deep and it involves ocean-going submersibles! Lake Baikal is pretty interesting in its own right though. Its home to one fifth of the worlds liquid freshwater, hundreds of unique flora and fauna including the Baikal Seal and was declared a UNESCO World heritage Site in 1996.
BBC News reports:

"Russian news reports said two manned mini-submarines successfully plunged 1,680m (5,512ft) to the lake's bed.

The mission is part of a two-year plan aimed at conserving the ecosystem of Lake Baikal, which contains about one-fifth of the world's fresh water.

(snip)

"This is a world record for a submarine diving in fresh water," Interfax quoted an organiser as saying.

(snip)

"There are technological problems, fickle weather conditions. Fresh water dictates its own special conditions," he said.

The two 18-tonne mini-submarines were designed to operate in seawater - but have shed hundreds of kilos to make them buoyant enough in less dense fresh water.

Mr Chilingarov also led a team of scientists to the North Pole in August last year - where they controversially staked Russia's claim by planting a flag on the seabed.

The BBC's James Rogers, at Lake Baikal, says the latest expedition is another sign of the Kremlin's desire to show the world the kind of feat a newly confident Russia is capable of."

There is also a little video of one of the Mir submersibles being lowered into the lake. It really adds nothing to the story, except there is a diver surfing on top of it...