Mraka Sound (Bulgarian: залив Мрака, ‘Zaliv Mraka’ \'za-liv 'mra-ka\) is a roughly rectangular water body extending 5 km in southeast-northwest direction and 4.2 km in southwest-northeast direction in Biscoe Islands, Antarctica. It is bounded by Renaud Island on the south, Pickwick Island on the north and Winkle Island on the northeast.
The sound is named after the historical region of Mraka in Western Bulgaria.