To get to San Carlos you can take a direct bus from the bus terminal in the north of Medellin. There are two companies offering the service: Coonorte or Transoriente. Buses leave every hour from 5 am to 5.30 pm. From the airport you have to go to Belen, to the highway and the buses pass there. If you are travelling from Guatape, you have to go to San Rafael and there is a bus at 9.30 am and another at 1.15 pm. It is a 1 hour journey.