Cole, check out the website for Belize---www.belize.org. This will give you some general info. re/ Belize. It is not an island but a small country in Central America.
I have been there a couple of times. Each time we were there we took a ships tour, seeing some Mayan ruins, cruising up a river and generally sightseeing. It is a beautiful country once you get out away from the town area.
If you would be more specific in what info you are looking for I'm sure there are folks out there who will be willing to help you.
Also, check out private tour company called cbelize.com - they offer a variety of tours. We used them for our one day tour and it was great. Keep in mind that Belize is very "undeveloped" compared to other more established ports. You might want to have an idea of what to do before you get there.
If you're interested in booking a tour on your own in Belize, I commend to you www.regtour.com.
I read a lot of good things about Reggie on various cruise boards, contacted him online and made plans for a tour of Belize City. While there wasn't a lot to see in Belize City itself, Reggie was reliable, very accommodating and reasonably priced compared to the same tours offered by the vruiselines.
Belize is a tender port, so allow plenty of time to get to and from shore. The tourist village is right at the port and offers a few nice shops including pharmacy, cigar store, souvenir shops and cafe's. As others have recommended, do your research and pick a tour before you get there. This is not a beach destination. However, there are tours and water taxi to Ambergis cay and Cay Caulker that are great for powdery beaches and snorkeling. Just keep in mind that transfer to these spots takes time and the water taxi does have a schedule. Reggie Trapp has been doing tours for more than 5 years. Make sure your private tour operator is reliable. His reputation is his marketing tool.
Check out the destination/port forums on these many great cruise web pages.
We did Reggie's Cave Tubing and had a great adventure.