Tvarditsa Rocks (Bulgarian: скали Твърдица, ‘Skali Tvarditsa’ ska-'li tv&r-'di-tsa) is a group of rocks off the north coast of Greenwich Island in the South Shetland Islands, Antarctica situated 1.9 km (1.2 mi) northeast of Ongley Island, 1.3 km (0.81 mi) southwest of Stoker Island and 2.6 km (1.6 mi) west of Sierra Island.