Chetumal is the capital of Quintana Roo in Mexico's Yucatán Peninsula. It is located on the Bay of Chetumal, a sheltered inlet of the Caribbean Sea at the mouth of the Rio Hondo. This bay, together with the Rio Hondo, forms the border between Mexico and Belize.
Lying by the border of Belize, Chetumal is much more than a mere travel hub between Belize and Mexico. It offers many, but greatly and fortunately unattended tourist attractions. Recently, efforts have succeeded in making the city more appealing to tourists. English is farily generalized, whereas Spanish happily coexists with Maya, Criole, Lebanese arabic and an impressive set of the growing multinational population of the City. There is a bit more than 260,000 Chetumaleños. The City of Chetumal is, both, the capital of the Free and Sovereign State of Quintana Roo, and the capital of the Municipio (County) of Othón P. Blanco. Othón P.Blanco is the only Municipio of México, that has land borders with two nations (Belize and Guatemala), thus sharing this characteristic with the state of Quintana Roo.
The city is officially founded by the military, in 1898, who had the mission of protecting the borders finally (after more than 50 years of disagreements) accorded by the governments of Mexico and Great Britain. A lot earlier, it had been a Mayan realm governed by Nachan Ka án. He was given two Spanish slaves, one of whom was Gonzalo Guerrero. Guerrero assimilated to his new society, learned the language and taught new war tactics to Nachan Ka án's warriors. With this knowledge, the warriors defeated incoming Spanish conquistadors and Nachan Ka án became a great leader. He made Guerrero a captain and gave him one of his daughters, Zazil Há. Guerrero and Zazil Há had many children who are known to be the first mestizos in America by matrimony. For this reason Chetumal is called Cuna del Mestizaje (cradle of the Mestizo).
Chetumal Airport (IATA: CTM) (ICAO: MMCM) offers a limited selection of flights to major cities in Mexico. It is also possible to fly into airports across the border, in Belize, and cross by land into Chetumal. Another option is to fly into Cancun or Merida and take a bus from the airport.
Mexico's Federal Route 186 traverses the sparsely populated southern half of the Yucatán between Escárcega and Chetumal. After Ucum, the only municipality with services such as gas and lodging between Escárcega and Chetumal is Xpujil. Federal Route 307 branches off Route 186 to the north towards Cancun, from a point about 30 km west of Chetumal.
Several bus companies offer routes across the Peninsula to Escárcega, or north to Cancun and other cities on the Mayan Riviera. The main bus terminal, i.e. ADO terminal, where most buses arrive to is located about two kilometers north of the city center (in the crossing of Av. Insurgentes and Av. Belice). There's an official taxi stand right outside the terminal, and a taxi to the center costs about 20 pesos.
If you're arriving from Belize, your bus might arrive to the New Market (Nueva Mercado). New Market is located about two kilometers northeast of the center, in the corner of 2do. Circuito Periférico and C. Veracruz. The bus fare from Chetumal to Corozal is BZD6 (as of Jan 2015). Bus driver will collect it after passing both the Mexico & Belize Immigrations.
Regarding exit tax at the Mexican border - if you reached Mexico via a commercial flight, you do not have to pay for the USD 25 (332 pesos as of Jan 2015).
By boat from Belize
There are two companies who will sell you tickets to Chetumal from the Belize Cayes. San Pedro Belize Express  and Belize Express Water Taxi's  both supposedly run a daily boat leaving Caye Caulker at 7am & San Pedro, Ambergris Caye at 8:00am. Tickets cost US$50 one way from San Pedro, US$55 from Caye Caulker. The return trip from Chetumal departs at 3pm. The terminals are located on the pier in front of Wahoo's Bar and Grill in San Pedro, in front of the basketball court in Caye Caulker, and arrive at the Municipal Pier in Chetumal (GPS 18.491682,-88.299204). Tickets can be purchased online at their websites - although there's probably no point booking ahead as in reality only one boat will run as there won't be enough customers. If you book with the "wrong" company you have the option to pay an extra US$10 to take other company's boat. Beware that these companies do not allow pets on the international runs to Chetumal. You'll have to go by land if you're travelling with pets (not clear on their website).
This trip will require you to pass through two sets of immigration. One to exit Belize and one to enter Mexico. If you travel with Belize Express Water Taxi from San Pedro the procedure is as follows.
If you're starting at Caye Caulker you will first take the boat to San Pedro where you will disembark. At San Pedro you will formally exit Belize. To do so you must pay 40 BZD (30BZD exit fee then two other port fees which make up the remaining 10BZD), this can be paid even in MXN or USD ($20) but the notes must be in good condition. If you don't have this money with you, there is a cash machine in San Pedro not far from the port.
You will then re-board the boat and leave for Chetumal. On arrival at the Mexican boarder you will have to complete arrival cards and pass through Mexican boarder control (this involves a very keen sniffer dog being present who is shown all luggage and passengers - don't risk it). Entry to Mexico will cost 390 pesos. This can be paid in USD ($25) or in pesos. It can not be paid in BZD.
There are a number of things that can help make this trip easier. Firstly, have the money ready before you leave Caye Caulker. If you have no USD or Mexican Pesos to pay your entry fee to Mexico, a staff member from the water taxi company will change your BZD in to Mexican Pesos or USD on the boat. If push really comes to shove, when you get to the Mexican boarder explain at the window that you have no cash and need to visit the ATM. They will hold your passport and luggage and allow you to exit the port and use the ATM which is at the bottom of the street (cross the road and there are two ATMs in an official looking building to the left).
If you are going on to Tulum, Playa or Cancun from here, the water taxi company will reserve you seats on shuttles which run straight from the port. Expect to pay $25 USD for Tulum and $30 USD for Playa. You can do this on the boat, then when you clear customs there is a small desk on the right where you pay your money. The vans will depart when everyone has cleared customs and they're sure there are no more customers!
These shuttles do not run on Sunday, so the procedure was as follows (April 2016): the shuttle company charges 504 Pesos each (to Cancun) and organizes you into groups, depending on where you are going. A total of 4 taxis, all packed full of people and baggage, drove together down the road, until some turned off for Tulum, Playa del Carmen, etc. The taxi took 5 hours to Cancun, including a stop for food/toilets. They waited until everyone had cleared customs before organizing the cars and getting as many passengers as possible.
A taxi stand for Chetumal is located down the street just behind the gate of Maritime terminal.
There are many archeological sites near Chetumal and they're relatively close to each other. The ones below are open 8-17 daily, admission only until 16:20. Bring a lot of water and some snacks with you as many of the sight stores are not always open. A mosquito repellent doesn't hurt either.
Cenote Azul and the Laguna de Bacalar are a 20 minute bus trip from the second class bus station. Tickets cost ~ 60 pesos although you may be able to pay less in a colectivo and just get dropped off at the spot along the highway. Entry to the cenote costs ~ 10 pesos. There is a restaurant and free wifi.
The public access point for swimming at Laguna de Bacalar is a long walk (>45 mins) from the cenote. There is a private property with stromatolites that charges a fee of 25 pesos for access to the water which is not far at all from the cenote, if you would like to swim in the lagoon without walking a long way, paying the fee at the private property would be strongly recommended.
To get back to Chetumal, return to the highway and hail down any one of the numerous colectivos returning to the city (25-35 pesos).
Chetumal is more and more becoming the Mesoamerican center of environmental friendly technologies. Efforts by individuals belonging to the private sector, in this direction, have begun to show signs of success.
Finding other than Mexican products from Chetumal is not easy. As there are not much tourists, most of the stores actually sell stuff to the locals.
If you're coming from Belize it's best to change your Belizean dollars to US dollars before you cross the border, this will give you a better rate and more places to exchange money. You can exchange USD to MXN in almost any bank at a good rate (Santander e.g.). If you happen to forget or just have a little left, here's a few places that can exchange Belizean Dollar to Mexican Peso. Keep in mind that this will not be the best exchange rate ever and they might only accept bills:
If you're going to Belize, you can just take USD. No need to exchange to BZD.
Typical local joints can be found here and there around the city, but there are basically no places on the main street Avenida Héroes between the Mayan culture museum and the sea. For fancier places go to Boulevard Bahía. The fishing village Calderitas' main economy is restaurant industry and you can find a lot of good seafood restaurants there.
Also the bar scene of Chetumal is quite thin. Boulevard Bahía has some bars.
There are at least 20 places to sleep in at Chetumal. Get a copy of a guide magazine from the Mayan culture museum or ask a taxi driver if you don't know where you're going. But if you have a booking somewhere, or you know where you want to sleep, it’s preferable to write down the correct address and give it to taxi driver to avoid confusion.
Chetumal is quite safe. Since there are not a lot of tourists, you can easily get through a week without anyone trying to fool you. Taxi drivers don't usually try to drive you into places more expensive than what you are looking for.
It's good to notice that English is not commonly spoken.
At the same main road you can also get a combi (mini van) to Mahahual (75 pesos each way may 2015, 1.15 min.), to Chetumal, and some other destinations around. It's not difficul to figure out where every combi is going, as they write down the destination at the drivers glass, and / or at the vehicle side.
There no departure tax when leaving Mexico, although charging a 200 pesos tax unfortunately is quite common. Look on the web for Mexican Belize Exit Fee Scam. Look at your airline ticket, which will show all required Mexico fees that have been paid and show this to the individuals at the border crossing. If they demand payment, tell them you will walk across the road to the big immigration building to notify someone in charge and they will usually hand back your passport and FMM papers and allow you to proceed across the the border.
Get on the Chetumal-Belize highway and drive to Belize.
To get a bus to Belize, you can either go to ADO terminal or New Market (Nueva Mercado), the latter being probably the better choice. Taxi drives usually know where New Market is, and nowadays also from where the buses leave. Bus from New Market to Belize City costs 90 pesos and runs farely often via Orange Walk where a break of 15 minutes is usually scheduled. These buses are older and have no A/C, and they stop often. Once you arrive to New Market, someone will approach you and tell about the schedules. These guys are working for the bus company and not just there to rip you off.
ADO terminal also has a service to Belize but it's less frequent and more expensive.
You can also get a boat from Chetumal to at least San Pedro from where you can continue to Caye Caulker or to Belize City. There are two water taxis, which both leave Chetumal at 3 pm, operated by San Pedro Water Taxi and San Pedro Belize Express.
A trip from Chetumal to San Pedro is US$47.50 on Belize Express Water Taxi  or San Pedro Water Taxi . Including preparation to depart, the trip should take around 2 hours (don't forget that Belize is an hour back from Mexico). August 2014 experience - booked online with Belize Express Water Taxi, but when I arrived at the office to check in I was told that they weren't running that day. San Pedro Water Taxi partially honoured my ticket after I paid an extra US$10. Arrived in Caye Caulker just after 6pm Belize time after going through customs in San Pedro and switching to a smaller boat.