I always prefer my own snorkeling gear (in a net bag for easy toting), and mask, if not fins. I've seen too many grotty used cheap snorkels that don't work well, too many masks that are hammered and won't work properly - snorkeling should be fun, not a hassle.

(BTW, late summer you can take a snorkel trip out of Cancún or Isla Mujeres to snorkel with whale sharks - I've been in the water with more than thirty sharks the size of small busses whilst they come and check me out, assume the heads up "bottle position" for eating plankton, etc. A-w-e some!)

Renting a car can be a hassle. Where I was born in the Capital, they only began demanding driver tests this year. most of the rest of Mexico ain't there yet. Road conditions can vary, rental companies can lowball you and charge you for fictional damages, etc. Check the rental thread out. Yet, I have rented... Though I can't recall from which company. (If you do rent, check all tires are good,mayor have a working spare and all tools... and use your cell phone to photo your car from all angles before and after.)