As a US citizen, you can travel to several beautiful island destinations without a passport, as they are US territories and considered domestic travel. These include Puerto Rico, the U.S. Virgin Islands (St. Thomas, St. John, and St. Croix), Guam, and the Northern Mariana Islands (Saipan, Tinian, and Rota). For these locations, you only need a government-issued photo ID, such as a Real ID-compliant driver’s license. Additionally, you can visit American Samoa without a passport, though it is technically an "unincorporated" territory that may require a certified birth certificate for entry. Another way to travel to islands without a passport is via a "Closed-Loop Cruise." These are cruises that begin and end at the same US port (e.g., a round-trip from Miami to the Bahamas). While the countries you visit might normally require a passport, US law allows you to board these specific cruises with just a birth certificate and a photo ID. However, this is risky; if you were to miss the ship or have an emergency that required flying home from a foreign island like Jamaica or the Bahamas, you would be unable to board a plane without a valid passport book.