Suggested way to go from Panama City to Belize, Cancun or Merida

Hello - My wife and i are going to visit Panama in February with friends. They are going back to Texas on Feb 15, the wife and I wish to continue our " scouting " of Central America from Panama City . We want to explore the Yucatan, and also Belize. I see that flying from PTY to any of these airports ( MID Merida, CUN Cancun and BZE Belize ) requires a trip back to the US ( Miami ) or elsewhere. Is there a " commuter" airline  that can economically get us to one of these destinations ? Any suggestions ?? We are young 62 year olds , so driving or buses or whatever could be considered. I just can't see paying $ 1500 for the two of us to get across central America.

Thanks for any input.

Have you check with COPA? IŽm sure they fly direct from Panama to Cancun, not sure of the price.

I know you can take a bus from Panama City to San Jose Costa Rica because many people do just that to fill the requirement of leaving the country for visa purposes. I would imagine you could also continue the journey from San Jose into Belize and I know you can drive from Belize in Mexico. I think I read in a blog somewhere that you can also fly from David to San Jose so I imagine you can also continue from there via air.

thanks for the replies, after deeper digging, I found an apple app for airlines in Mexico and Central America which helped a lot. We're going to restrict this first trip to exploring Panama from top to bottom. We will then regroup and plan next trip to Yucatan/ Belize.