Australia and Antarctica.
Australia and Antarctica are the two continents that lie entirely in the Southern Hemisphere.
More information:
➤ Australia:
The continent of Australia (also known by the names Sahul, Australinea, or Meganesia) is a geographical region on Australia's continental plate. It is the smallest of the seven continents.
It lies in the Eastern and Western Hemispheres but completely in Southern hemisphere.
The continent of Australia has a land area of 8.52 million km² and a population of over 41 million.
The continent of Australia consists of countries like Australia, Papua New Guinea and some portions of Indonesia.
➤ Antarctica:
Antarctica is the 5th largest & southernmost continent of the Earth. It contains the South Pole and is situated in the Antarctic region of the Southern Hemisphere. It is nearly twice the size of Australia.
Antarctica has an land area of 14.2 million km² but 98% of it is covered by ice. The Antarctica's population is mostly seasonal and would be around few to 5,000 people. It is a virtually uninhabited.
The peninsula’s isolated terrain also shelters rich wildlife, including many penguins.
The largest city of Antarctica is McMurdo Station, a research stations.