Caye Caulker has long been one of the premier destinations for travelers to Belize. This small island town is located about 15 miles north of Belize City and is close to the barrier reef. It is easily accessible by water taxi or with frequent domestic air service. Caye Caulker has retained much of the laid back, funky Caribbean flavor of days gone by, and the huge boom of tourism and development have largely passed it by. The streets are still unpaved, and Caye Caulker culture attracts the backpacker crowd and those wishing a more casual island experience. Lots of tours are available, including a local rasta style tour operation which offers 3 day party trips aboard a sailboat, camping on various islands and snorkeling from the boat as they travel around down the barrier reef.
Accommodations vary from very cheap, hostel type guesthouses to some newer, slightly fancier hotels along the waterfront. Everything is still much less expensive than the big resorts on Ambergris Caye and Placencia, and one can get by on fairly little if that is what your budget dictates.
I was just there and the best place to stay on Caye Caulker (IMHO) is the Caye Caulker Condos. It is reasonably priced at $85/night US, and is modern, with a/c, full kitchen, balcony, pool, and located on the sea. Plus it is one of the last places on the north end of the main street so it is much more quiet than other choices. The Caye Caulker Condos are the 3 story building on the left, below.