Atlantis? That location is open water, 34 miles SSE of Ahunui, a teeny atoll in the south Pacific, part of French Polynesia...but I suspect you knew this.
Australia is at 20 degrees south and 140 degrees east.
Antarctica
A location at 20 degrees south and 140 degrees east falls in the Pacific Ocean, southeast of Australia and northeast of New Zealand. It is in an area known for its remote and uninhabited islands.
20 S 140 E is Three Rivers, Queensland 4824, Australia. So the continent is Australia.
Since you did not specify the direction of longitude, the country located at 20 degrees south latitude and 140 degrees east longitude is Australia, while the country located at 20 degrees south latitude and 140 degrees west longitude is France. The location is French Polynesia, which is a French territory.
Virtually the entire 80°S parallel is on the continent of Antarctica or its waters.
The coordinates 20 degrees south and 140 degrees east are located in Australia. This point is situated in the northern part of the continent, specifically in the Northern Territory. Australia is the only continent that falls at those specific latitude and longitude coordinates.
The location at 20 south latitude and 140 east longitude is in Kajabbi which is a small settlement in north west Queensland, Australia. This location is just less than 5km northeast from the Kajabbi Airport.
South Pacific Ocean
Australia
The coordinates 20 degrees South and 140 degrees West lands somewhere between the islands of French Polynesia. The islands of French Polynesia are in the South Pacific Ocean.
Namibia