American citizens may travel to Jamaica as tourists (with U.S. passports) for a period of up to six months. Visitors must be able to demonstrate a return ticket to the U.S. as well as proof, if requested, that they have sufficient funds to support their Jamaican vacation. U.S. Passport Cards are an acceptable document for entry into Jamaica for visitors arriving and departing by sea only. If you're traveling for work or planning an extended stay, you must also have a visa. Travelers must pay a departure tax, which is generally included with the purchase of a plane ticket. Further and updated information regarding entry and exit requirements is available from the Embassy of Jamaica, whose website is embassyofjamaica.org.
Pack clothes for a warm climate. Jamaica boasts a humid tropical climate, with an average temperature range of 66 to 99 degrees Fahrenheit. If you're sun-sensitive, it's a good idea to bring along a couple of very light long-sleeved shirts (white linen is a good choice) to shield delicate skin from the harsh tropical sun. Rain is common all year, especially through the island's two rainy seasons (May to June and September to November), so make sure to pack rain gear. Definitely bring your sandals as Jamaica is a very casual place.
Jamaica operates on the Jamaican Dollar. It's important to carry some cash to change on arrival, but obtaining cash isn't difficult. Most ATMs in the country accept international bank cards, as long as the ones that you bring along are in the Visa, MasterCard, Cirrus or Plus networks. If you opt to bring traveler's cheques, brick-and-mortar banks in Jamaica are able to change them for you, as well as arranging cash advances with major credit cards.