the staff. All meals and activities are included (jet skis, paddle boards, snorkel/scuba, spear fishing, deep sea fishing, you name it). Plus they have all kinds of hammocks around the island to pick out and rest on.
http://www.royalbelize.com/
It's all inclusive, 4 night minimum. Standard rates are about $4k/night in the off season ($5k/night peak season, or $7k/night around Christmas), but it's worth it.