Living thousands of meters beneath the ocean means being able to withstand below freezing temperatures and pressures in upwards of hundreds of atmospheres.

From Seanews.com

Like many deep sea fish, S.microcephalus utilizes toxic compounds that would be and are deadly to other organisms in order to stay alive. One compound that the Greenland shark uses is trimethylamine oxide (TMAO), and in excess. They contain as much as 1% of their flesh weight in TMAO, between 1·05 and 1·30 g (TMAO)/100 g−1 material (MacNiel et al 2012). TMAO has been proposed to prevent organisms from freezing by increasing osmotic pressure in tissues and lowering the freezing point of water in the body (Seibel & Walsh 2002).

TMAO is also used in elasmobranchs to counteract the destabilizing effect large concentrations of urea have on their enzymes. Because they are osmoconformers, sharks retain a large amount of urea in their fluids to maintain cell structure(Seibel & Walsh 2002).

In addition, TMAO also has a hand in protecting organisms from extreme hydrostatic pressure, also playing a protective role over enzymes, though exactly how that is achieved is unknown(MacNiel et al 2012).