Mariana Islands (sometimes called The Marianas; up to the early 20th century sometimes called the Ladrone Islands) are a group of islands made up by the summits of 15 volcanic mountains in the Pacific Ocean.

They are the southern part of a submerged mountain range that extends 1,565 miles (2,519 km) from Guam to near Japan. The Marianas are the northern most islands of a larger island group called Micronesia. The Marianas have a total land area of 396 square miles (1026 km²). Guam is a United States territory, and the rest of the Mariana Islands are a United States of America commonwealth called Northern Mariana Islands.

The first European to discover the island group was Ferdinand Magellan in 1521. In 1667 Spain formally claimed them, and named them after Spanish Queen Mariana of Austria.

Following the Spanish-American War, Spain ceded the southern part of the group to the United States, and sold the northern remainder to Germany. After World War I the former German islands were entrusted by the League of Nations to the control of Japan.

The island chain saw fighting between the US and Japanese forces in 1944 during World War II. The United States wanted to capture the islands for use as a bombing base to raid the Japanese mainland.