Supposedly someday there will be one on north Ambergris Caye, here is some discussion about it...
https://ambergriscaye.com/forum/ubbthreads.php/topics/514606.html
Article Number: 463
Author: Wed, Nov 23, 2016
Last Updated: Wed, Nov 23, 2016
Author: Marty Casado
Online URL: https://ambergriscaye.com/help/article/what-is-the-status-of-belize-having-a-second-international-airport-463.html