What is 'vymorozka', called 'one of the hardest jobs in the world'?

The process of 'vymorozka,' which roughly translates as 'freezing out,' refers to the weeks-long tedious work by Siberian shipyard workers to maintain the hulking vessels in temperatures dropping to -50°C. Workers chip away at the ice encasing the ships, looking for areas in need of repair. The task is often called one of the hardest jobs in the world.