record-breaking attempt to reach the bottom of the world's deepest lake, Lake Baikal in southern Siberia.

A team of Russian scientists says it has succeeded in a record-breaking attempt to reach the bottom of the world's deepest lake, Lake Baikal in southern Siberia.

A manned submarine plunged nearly 1,700 metres to the lake bed.

Lake Baikal contains a fifth of the world's freshwater and is home to hundreds of unique aquatic species.

Research gathered during the expedition will be used to produce better conservation policies for Lake Baikal, which was declared a UNESCO World Heritage site in 1996.