This small town is off the beaten track but is quiet and friendly and has good diving. For good food and company I recommend: The Thai restaurant (internet, but watch out for the Moxy's squishy nose and sharp claws; Travellers' Rest; Xtanca bar and restaurant (internet and great mescal) – I will be surprised if you find warmer, broader smiles than those of David and Carmen.
If you are interested in conservation ask for directions to GVI (Global Vision International) at the south end of town. This is the base for marine conservation work carried out by a young and enthusiastic group of full-time staff with the help of 16 volunteer divers, in liaison with Mexican partner organisations. Staff and volunteers are from around the world; they will be happy to tell you about the project and how you can become a volunteer yourself. Whilst the majority of volunteers are in their twenties, there were a few in their thirties and I was 58. I spent 5 weeks on the Mahahual project at the end of 2004 and had a great time. Food and living conditions are basic but the experience is unbeatable.
Playa del Carmen, Yucatan: I thought I would not enjoy this purpose-built tourist town having lived in the sleepy backwater of Mahahual for five weeks, but I loved it. It is lively and colourful with endless shops and restaurants, some funky places to stay (eg Casa Toucan), a great beach and the scuba-diving there was excellent – on a single dive I saw 9 enormous turtles and species I had not seen during 5 weeks further down the coast. This is gentle drift diving. I dived with Beach Divers (on the sea front, near the ferry) and the service was great. As well as diving off the coast, I also did two cenote dives with Beach Divers and Jose who took me on these mystical dives even brought home-made sandwiches, bless him!
I noticed that Wikipedia Travel did not have a Mahahual page, so I created one and with just minor editing, copied what you wrote as the beginning of one. Feel free to edit this as you wish.
