KMarie, did you have a look at my BelizeBus site?
I thought I had done a pretty good job of detailing the trip step-by-step.
There are no direct buses to Chetumal from the airport, as far as I know.
From the airport, you can get a bus north to the bus terminal in Cancun, or south to the bus terminal in Playa del Carmen. At one of those places, get a bus to Chetumal. I do the Playa route.
This is how I do the trip from Cancun airport to Chetumal…
From Cancun airport to Playa del Carmen, there is an approximately hourly ADO Riviera airport shuttle bus. The first three departures after 10:58 am are 11:15, 12:00 & 12:40. Cost is MX$106 (that's pesos) and the trip takes 1 hour.
Tickets are sold at a counter in the airport just after exiting customs or, if there's no one there, from the ticket seller where the bus is parked. To get to the bus, go out of the airport terminal, turn right and keep going to the other end of the terminal (this might depend on which terminal you arrive at, but I'm guessing this is correct).
There are 2 bus teminals in Playa. The airport shuttle bus terminates in Playa del Carmen at the bus terminal at the corner of Quinta Avenida and Avenida Juarez (5th Avenue and Juarez Avenue). If you want to continue to Chetumal immediately, get a taxi (MX$15 to MX$20) to the other bus terminal (Terminal Alterna) at Avenida 20 and Calle 12, where the bus departs to Chetumal. Sometimes the airport shuttle bus will stop at the Alterna terminal before continuing to the terminal on 5th Avenue). Check with the driver or watch the street signs in Playa, and if the bus stops at Alterna and you want to continue to Chetumal, get off and change buses.
Or, stay a night in Playa. If you decide not to stay in Playa, there are plenty of hotels in Chetumal.
Here’s a link to a map of Playa del Carmen showing the location of the two bus terminals:
http://www.travelyucatan.com/playa_del_carmen_mexico_hotel_map-a.phpFrom Playa del Carmen Terminal Alterna, ADO express buses depart frequently to Chetumal. The trip takes about 4.5 hours and costs MX$228 for Primera Class (as at July 2010). Check the ticketbus site for up to date schedules and fares.
http://www.ticketbus.com.mx/wtbkd/index.jspThere are two water taxi companies providing service between San Pedro and Chetumal:
a) San Pedro Water Jets International:
http://www.sanpedrowatertaxi.com/index.htmlb) San Pedro – Belize Express:
http://sanpedrobelizeexpress.com/index.htmlTrip time: 90 minutes.
Fare: US$30 one way, US$55 round trip.
Despite what their websites state, this is the information I have received directly from the water taxi companies. When daylight saving is in effect in Mexico, SP Water Jets departs Chetumal at 3:30 pm Mexico time (2:30 pm Belize time), and SP-B Express departs Chetumal at 4:30 pm Mexico time (3:30 pm Belize time).
In Chetumal, water taxis use the main pier, “Muelle Fiscal”, which is close to the big Government building, “Palacio Gobierno”, at the waterfront. Check the map of Chetumal above for the locations of the ADO bus terminal and the pier. The pier is also visible on Google Earth.
If arriving in Chetumal at the ADO bus terminal, there is a little booth inside the terminal where you can get water taxi information. There is (or at least there once was) a water taxi sign and a person who speaks English. You could probably buy a ticket there, but you might get pushed into an overpriced taxi. I’d just go outside to get a taxi, and buy a ticket at the pier.
It’s about 3.5 km from the ADO terminal to the pier. A taxi should take about 10 minutes, and cost about MX$15 to MX$20 (that’s pesos), and certainly no more than MX$30. The taxi driver might not know about the water taxi, but he/she will know the pier. Write it down if you can’t pronounce it.
The BelizeBus site has a map of Chetumal showing the location of the ADO bus terminal and the water taxi pier.
For the return trip, there is a direct bus from Chetumal to the airport -- it departs around 11 pm or 12 midnight -- check the ticketbus site for schedule & fare.
How's that?