There are not any flights to Belize from Cozumel. The best way to do it is take the ferry boat to Playa and from there take the bus to Chetumal. Chetumal is right at the border. From there, you can take a cab over the border to a little town called Corozal. There is a small airport there that has flights over to San Pedro which is where much of the diving is. A flight was about $35-$45 one way 3 years ago. Check on google for flight schedules, I think the airline was maya air if I am not mistaken. Get a very early start out of Cozumel, otherwise you may need to stay the nihgt in Chetumal or Corozal until the next flights begin. Have a good time!

tom@hotelflamingo.com