All U.S. citizens traveling to Bermuda by air must present a passport book or other valid travel document. Other valid U.S. travel documents that are WHTI-compliant include a trusted traveler card, enhanced driver's license, US military ID with travel orders and a Native American tribal ID card.
A passport book or passport card issued by the United States are acceptable forms of identification for travel to Bermuda by sea, as are the WHTI approved documents accepted for air travel. U.S. passport cards are only valid for travel to countries under the WHTI but may be less expensive and faster to obtain than passport books.
For children under 16 years old, an original or copy of a U.S. birth or naturalization certificate is an acceptable form of identification to travel to Bermuda and to re-enter the U.S.
The Department of Homeland Security recommends reviewing information on their website for travel document requirement changes. You may search the database for Bermuda or other specific countries.