First you need to get from Cancun to Chetumal on the Mexican side of the border. Second you need to cross the border and go to Corozal Town on the Belize side of the border. Third you need to get to San Pedro.
You can fly (in theory) or take a bus from Cancun to Chetumal (5 hours, $20 dollars).
You then take a different bus ($1.50) or a cab ($25) across the border to go from Chetumal to Corozal Town.
You can then fly ($35) or water taxi (??) from Corozal Town over to San Pedro.
Personnally I get tired just saying it...
#97151 - 02/15/0503:27 AMRe: Getting to San Pedro from Cancun
one more thing: when you get off the bus in chetumal, you go outside to the taxi lineup and take a taxi to the new market. the bus to Belize dosent leave from the bus station. and it is a taxi ride, didnt cost much, but you sure couldnt walk it.
#97152 - 02/15/0508:46 AMRe: Getting to San Pedro from Cancun
My experience: Most of the Novelo's buses to Corozal and Belize City do leave from the main terminal in Chetumal. They stop at the ADO/main terminal after leaving New Market. It's only the early morning buses that don't. Why that is I don't know. When you come in to the main terminal on ADO, ask to see if you need to take a taxi to Nuevo Mercado or not.