Just relax and enjoy the beach. The water is as blue as the brochures. Go to Isla Mujeres. Garaffon Park is beautiful.
Quick Tips:
if you need to shop, Wal-Mart is downtown. There is a market downtown for souvenirs although the prices are better on Isla Mujeres. If you take the Fast Cat to Isla, it is quite a few blocks to downtown.
Best Way To Get Around:
The buses run regularly and they are inexpensive. Not too hard to find your way back as the Hotel is just outside the enormous Flag Pole (although I never did see a flag up).
If you take a taxi from the hotel . . . the price is set at the hotel. DO NOT ask the man how much you owe him when you arrive at your destination . . . or you WILL get charged more.