Snorkelling/Ruins etc. - need advice

[escapingcold]

Hi there.

I will be going to Playa del Carmen for a week over New Years. Having gone on a few cruises, I have decided to try an all-inclusive for a change.

I am hoping that you all can help me out.

My husband and I want to go snorkelling while we are there plus we want to visit some ruins, among other activities.

So: here are my questions:

1) Where should we snorkel and which tour company should we use?

2) Which ruins should we visit? (I am not sure we would want to visit more than one site)

3) What are the MUST sees and dos in the Mayan Riviera?

Thanks!