The largest region on Earth depends on how you define "region".

* By Land Area: Asia is the largest continent with a land area of approximately 44,614,000 square kilometers (17,229,000 square miles).

* By Total Area (Land and Water): The Pacific Ocean is the largest oceanic region with a total area of approximately 165,250,000 square kilometers (63,800,000 square miles).

So, the answer depends on your perspective!