Prior to 2007, citizens of the U.S., Bermuda, Canada and Mexico could travel between those nations by air, land and sea without having to show a passport. Because of tightened security after 9/11, the law now requires that all U.S. citizens show a valid passport or other documents accepted by the State Department if they leave and re-enter the country. All non-U.S. citizens must show a valid passport or acceptable identification to enter the United States, regardless of entry point. U.S. citizens do not need to have a passport to travel to Hawaii, since they are still traveling within their country. All other visitors must show a valid passport when traveling to Hawaii.
There are different visa requirements for visitors to the U.S., depending on their country of origin and planned length of stay. Check the U.S. State Department website for an updated list of requirements by country. This site will also provide visa information depending on the purpose of your visit, such as student visas, temporary work visas, tourist visas or visas for those who plan to move to the U.S. permanently.
If you are a U.S. citizen, visiting Hawaii is like going to any other state, except that you have to fly across the Pacific Ocean to get there. If you are planning on visiting Hawaii from another country, then the same passport and visa requirements apply as anywhere else in the continental U.S. Before you book your trip, be sure that your passport is up to date and check visa requirements to be sure you allow enough time for visas to be processed before leaving on your trip.