Profound Lake (formerly known as Lago Glubokoe or Glubokoye) (62°11,066'S;058°54,413'W), is situated on Fildes Peninsula, the largest ice-free area (29 km2) of King George Island, the largest of the South Shetland Islands, located in the extreme southwestern part of the island. This lake lies 500 m from the base of the Collins glacier, close to the Uruguayan research base (Artigas) and Maxwell Bay. Morphologically it has a surface area of 90 km² and 14.7 m maximum depth. It's a holocenic, non-impacted, pro-glacial lake where diatoms are abundant and diverse.This organisms present a cell envelope, external to the plasma membrane, composed of rigid structure impregnated with silica called frustules, resistant to dissolution, that allow their preservation in sediment layers in the long term. These characteristics enable the use of diatoms in paleoenvironmental, paleoclimatic and paleoecological studies, thus we use the relative abundance of this organisms in a sediment corer in order to calibrate and evaluate the use of them as a proxy to reconstructed Ozone variability iin Antarctica.