My plane landed in Cancun around 7:20 am and I finally arrived in San Pedro around 5:45 pm (6:45 pm Cancun time). The bus ride to Chetumal alone was almost 6 hours (with stops in PDC, Tulum, and Felipe Carrillo) and that doesn't include the transfers and going across the border. Much longer than I thought it would be, but I did get to see the countryside and have a lot of info on travelling that route. On a brighter side the cost of all this was about $45 (which includes a $20 ride from the Cancun airport to the bus terminal). I bought a RT ticket on Maya airlines to San Pedro for $65 US. The last two flights out were at 5 and 5:30.