sentences:  On 5 February 2012, a team of Russian scientists completed the longest ever ice core of and pierced the ice shield to the surface of the lake.The first core of freshly frozen lake ice was obtained on 10 January 2013 at a depth of .However, as soon as the ice was pierced, water from the underlying lake gushed up the borehole, mixing it with the Freon and kerosene used to keep the borehole from freezing.