An image of Afro-Eurasia, the largest landmass on Earth. A landmass, or land mass, is a large region or area of land that is in one piece and not noticeably broken up by oceans. [1] [2] The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or a large island.[3] [4] In the field of geology, a landmass is a defined …