What is there to do activity-wise in this area? I am looking for relatively inexpensive activities: horse-back riding, snorkeling, rafting, hiking, stuff within driving distance. Is renting a scooter/car advised?

You should check out a great PDC site: www.playadelcarmeninfo.com for lots of great stuff...

Hi

My wife and I went there a couple of years back and I have posted a trip report with pictures on my homepage www.gardkarlsen.com. Maybe you can find some useful information there

regards
Gard
Stavanger, Norway

There are plenty of things to do and can usually be organized by the hotel. The scuba diving is quite nice and the Mayan ruins are a must. Some people like to venture over to Cozumel for even better diving and snorkelling, but dending on how much time you have, you may prefer to just enjoy what's close. We also saw people riding bikes into town from the main strip - it's only a short 5 -10 min cab ride, but a nice tour on a bike.

Tons to do:
1. Mayan ruins in Chitzen Itza and Tulum
2. Ecological tours in Xel-Ha and Xcaret
3. Ferries to Cozumel and Isla Mujeres
4. Explore Cancun
5. Snorkeling, esp. in Cozumel
Can't say about auto rental. We never had the occasion to.
Have a great time!