horse back riding on the beach

It will just be my mother and I cruising this march ports are mahogany bay, Belize, and Cozumel. Any suggestions for great horseback riding on the beach? This is my mom's one must do on this trip. Please any suggestions or advise would be great?

google El Rancho Barrio Dorcas or Anthony's Keys. These may be ship based excursions only. If so, contact your cruise line. You can also go out to Victor Bodden's site. He has offered a horse back riding option in the past when you customize your tour with him.