Just a note of caution to travelers booking independently via VRBO and other such sites.
Although the majority of listings are legitimate, some are for properties that are not licensed, not qualified to supply the services they provide and may not carry liability insurance - all of which are required by the Belize Tourist Board. If a "by owner" offers you a package including for instance, snorkeling, check to be sure that you will be going out with a licensed professional tour guide and licensed tour operator. You deserve not only fun, but a safe venture under the sea.
If food is part of the offering be aware that they need food handlers licenses and health checks. Be sure these are in place as well.
If you don't want to bother investigating these things then a you may want to consider using the services of a qualified travel agent who will only book you into situations that are legitimate, safe, healthy and good values.
This cautionary note could be applied to virtually any location..... Licensing of accommodations and other such services is meant to protect the consumer. Please patronize the establishments that honor this intention.