Soldiers are required to be in uniform at all times while representing the U.S. Navy, unless given permission to wear casual attire by a commanding officer. There are variations to the uniform, but in general it includes slacks, shoes, an undershirt, a button-down shirt, and a cap. Acceptable materials for the uniform frequently change; consult the U.S. Navy's official website for up-to-date information on current fabrics used in uniforms, as well as other uniform-related regulations, including penalties for uniform violations.
When not on ship, a soldier must wear the appropriate headgear for a given situation unless he is given orders to remove it, if he is attending a religious event that is not a military ceremony, or if wearing headgear would endanger him. Headgear is not required while on a ship unless the soldier is ordered to wear it or is attending a military ceremony.
Soldiers are not permitted to wear skirts or high heels while on ship under any circumstances; however, soldiers may stow these items on board for later retrieval. V-neck and sleeveless undershirts can be worn under special circumstances, as can sweaters and poromeric shoes. Polyester uniforms are not to be worn during any activity that involves sparks or open flames.