The western frontera into Guatemala  is only 11 miles from San Ignacio , a trip made for around US$3 per person in a colectivo taxi, less in a passing bus bound for Benque Viejo . A private taxi from San Ignacio should cost about US$15 total.
Be prepared to pay your US$19 exit fee on the Belizean side, which includes the PACT fee (they will ask for exact change); the rest of the money goes to the private “Border Management” company, a point of contention for local tour providers and would-be Guatemala day-trippers.
Expect the usual throng of money-changers to greet you on both sides of the border—they’re fine to use, as long as you know what rate you should be getting—or you can use the official Casas de Cambio on either side.
If you’re driving your own car, make sure you have all the necessary papers of ownership and attendant photocopies of all your documents, including license and passport, which they will want to see. You are required by law to have your tires fumigated when entering/exiting Belize and Guatemala, for which the cost is a few Belizean dollars.
If driving a private or rental vehicle into Guatemala you will have to pay a “toll” to cross the bridge going over the Mopan into Melchor. If your car has Belize tags, the fee can be as low as 5 quetzales. If your tags are from far away, like Canada or the United States, be prepared to pay Q50 and not one peso more. Save the receipt if you are returning to Belize, as it is good for a two-way crossing.
In addition, based on some reports travelers have to ensure that they have received a proper exit stamp when leaving Belize, for both themselves and their vehicle. Double-check your passport before continuing on to Guatemala.
After clearing Guatemalan immigration and shaking off the sometimes aggressive taxistas, you’ll find yourself on the edge of the Mopan River, across which begins the town of Melchor de Mencos . Before crossing the bridge, you’ll find the Río Mopan Lodge (tel. 502/7926-5196, www.tikaltravel.com , US$20) on your left, a nice riverside hotel and restaurant whose proprietors (a Swiss-Spanish couple) are a wealth of information on remote ruins in the area.
There are other places in Melchor if you get stranded in town for some reason or are embarking on your own jungle expedition to unexplored ruins.