Here is a photograph of the lake by the village of Kilpisjärvi, taken on the day the crew arrived (9th May 2011).
One would be tempted to say 'Kilpisjärvi Lake', but that would be tautological, as 'järvi' means 'lake'. The Könkämäeno River flows out of this lake and the waters then join first the Muonio River and then Torne River, before finally flowing into the Gulf of Bothnia.
As you can see, when the photograph was taken, the surface of the lake was still frozen. But it is thinning out in places and has started to fracture, especially around the shoreline.