A good discussion about traveling alone to Belize on the Lonely Planet forums.
"...Hey everyone, I'm taking a trip (starting in Cancun) for the university break. I'm planning on arriving in Belize December 26, and probably leaving Belize January 3. If anyone else is traveling alone or in a small group and wants to meet up let me know. Also, if anyone has any personal experience or advice on the best places to go, things to see feel free to let me know...."