Belize City is the largest city in Belize. It is located on a small peninsula protruding into the Caribbean Sea. It was the capital city until flooding and other damage from a hurricane prompted the government to relocated to Belmopan, nearer the geographic center of the country.
The international airport (Philip S. W. Goldson International Airport[]) for Belize is located in Belize City. Philip S. W. Goldson is about 30 minutes drive from Belize City's center. The best way to get to and from the city center is with a taxi. Although an airport bus service exists, it is very infrequent and unreliable. BZE (Philip S. W. Goldson International Airport) is served by most major US airlines (American, Delta, Continental, and US Air) as well as a couple regional carriers (Honduras, Maya, and Tropic).
San Pedro Express and other water taxi companies have boats going out to Caye Caulker and San Pedro from the city often. Remember if you buy a round-trip ticket, you will have to use the same company going back as you took going there.
From Guatemala City (travel time: 8 to 10 hours), you have the following options to Belize: Altobuses del Norte (ADN) . Linea Dorada , first class buses leaving Guatemala City at 9:00pm for US$30,"first class" buses at 10:00am and 12:00pm for US$22 and an economy bus leaving at 10:00pm for US$16. Fuente del Norte  has 15+ departures from Guatemala City per day. Most of these are local runs with second-class buses (older pullman coaches without air conditioning), but they also operate a few first-class express buses (with toilets and air conditioning) leaving from Guatemala City at 10:00am, 2:00pm, and 10:30pm, and a deluxe bus leaving from Guatemala City at 9:00pm.
Use a taxi. If you want to get out of Belize City, use the taxi, bus, or even the little airplanes which take you to other destinations in Belize for less than US$100.
Getting to and Around the Cayes Belize is undoubtedly the “it” place in travel and tourism in Central America and the Western Caribbean. Not only is the culture attractive for foreigners as an English speaking nation, navigating to and around the Cayes of Belize has become very easy. For those wanting a truly Belizean experience, take the water taxis from destination to destination. San Pedro Belize Express  departs from the Brown Sugar Terminal in Belize City with scheduled runs at 9:00 a.m., 12:00 noon, 3:00 p.m. 5:30 p.m. to San Pedro and Caye Caulker.
Departure to Caye Caulker and Belize City from San Pedro Town pier on Black Coral Street next to Wahoo's Bar and Grill and leaves at 7:00 a.m., 11:30 a.m., 2:30 p.m., 4:30 p.m.
There are boats departing from Caye Caulker to both Belize City and San Pedro Town and they leave from the pier in front of the Basket Ball Court. Caye Caulker to Belize City: 7:00 am, 12:00 pm, 3:00 pm, 5:00 pm and Caye Caulker to San Pedro: 7:00 am (Connection to Chetumal), 9:45 am, 12:45 am, 3:45 pm
Rates: Belize City to San Pedro, San Pedro to Belize City: $30 Belize or $15 US (one way), $55 Belize or $27.50 US (round trip) Caye Caulker to San Pedro, Belize City to Caye Caulker: $20 Belize or $10 US (one way), $35 Belize or $17.50 US(round trip)
There is not much to do around Belize City, and most use this as a transportation hub. With that said, there are a few museums around the downtown area and a zoo.
Most places accept US Dollars as the Belizean Dollar is pegged to the US dollar at 2BZD = 1 USD. If you are traveling to the cayes, stock up on your cash at the central bank, as the ATMs on the islands often run out of money on weekends.
If you want to shop there is tourism village in the Fort George area which has jewelry shops like Diamonds International and lots of gift shops. Fort George is located on a boardwalk.
There is a cruise terminal there that receives Carnival Cruise Line ships.
The Western Highway leads to Belize West or the Northern Highway to Belize North.
San Pedro Belize Express  departs from the Brown Sugar Terminal in Belize City with scheduled runs at 9:00 a.m., 12:00 noon, 3:00 p.m. 5:30 p.m. to San Pedro, Ambergris Caye and Caye Caulker.
Rates: Belize City to San Pedro, San Pedro to Belize City: $30 Belize or $15 US (one way), $55 Belize or $27.50 US (round trip), Belize City to Caye Caulker: $20 Belize or $10 US (one way), $35 Belize or $17.50 US(round trip)
(Personally,) I would recommend a week-long trip to Green River in the south to experience the rain forest and a week-long trip to the coral reefs to experience the reefs.