It’s taken years. You’ve slowly been checking everywhere in the United States off your list. You started with the 50 states—including Alaska and Hawaii. You visited Washington, D.C. You stopped in the US Virgin Islands and Puerto Rico. And you finally made your way to American Samoa and Guam in the South Pacific. Your checklist is complete. Almost. Don’t forget the Northern Mariana Islands.

The Northern Mariana Islands are often forgotten on the list of US commonwealths and territories. They’re located in the western Pacific Ocean, three-quarters of the way between Hawaii and the Philippines. Only three—Saipan, Tinian, and Rota—of the 15 islands are inhabited. Saipan, the most populated island, is the one most people visit. But it’s Tinian, across the Saipan Channel, that really deserves a stopover.

Tinian has a fascinating history. Artifacts found on the island show that it’s been inhabited for more than 4,000 years. Spanish explorers “discovered” it in 1522, and later built a large port and ranches on the island, before selling it to the Germans in 1899. The island was captured by the Japanese during World War I and was seized by the Americans during the Battle of Tinian during World War II. They covered most of the island with a huge airbase. It’s now mostly overgrown and surrounded by limestone cliffs, perfect beaches, clear water, and vibrant coral reefs.

You land at West Field, outside of San Jose, the largest village. The airport’s runway was built by the Japanese, and the Americans later used it as a departure point for reconnaissance missions in Southeast Asia. Stop at the Korean Monument, which honors the Koreans killed during the Battle of Tinian. See the House of Taga. Its prehistoric latte stone pillars continue to puzzle historians. Drive along the southern shore to Suicide Cliff. Japanese soldiers jumped from the cliffs, after the Americans seized the island, out of fear they would be tortured.

Driving north along the eastern shore, you see Mount Lasso, the highest point on Tinian, to your left. At the Tinian Blow Hole, massive columns of water spurt into the air from water entering a limestone ledge. Head inland to the Shinto Shrine. The last Japanese shrine on the Northern Mariana Islands is mostly covered by thick vegetation, though you can see the steps leading to it. And then go to North Field. The World War II runway was where the Enola Gay and Bockscar departed, carrying atomic bombs that were dropped on Hiroshima and Nagasaki, respectively. The runway is now used for artillery training, and you can visit the memorial in the old loading pits and a Japanese fuel bunker.

Exhausted from a long day, you make your way down the western coast. Tomorrow you’ll hike Mount Lasso and look for Tinian monarchs, the island’s only endemic bird. You’ll scuba dive among war tanks and ammunition at Dump Cove, and then a Japanese canon and sea turtles at Turtle Cove. You’ll hop between the smaller beaches: Tachogna, Kammer, and Chulu. But tonight, you’re going to watch the sun set from Taga Beach. It may be the most popular beach on the island, but after a day heavy with history, you’re ready for some Chamorro food and friendly smiles. Then your mission will be complete.