I am also planning a similar trip this year in July.
4-5 days in Isla Mujeres (3 days swim with WS)
4-5 days in Cancun or Playa Del Carmen (3 days diving Cenotes)
Few days topside travel
This is a big trip for me , travelling from Oz.
I have a few questions.
1. Is it worth travelling to Cuba/Havana for 2 -3 days (UK passport). Would i be able to arrange travel package to Havana from a travel agent in cancun for this trip.
2. What is best place to stay for 3 days diving Cenotes (Cancun or PDC?)
3.For topside attractions is it better being based in Cancun or PDC , e.g for day trip to Chichen Itza
4. Any hotel recommendations for PDC/Cancun or IM?
1. Cuba has some beautiful postcard beaches, almost everyone stays at all inclusive resorts. Lots of Canadian's as it's the cheapest "Caribbean" destination. Havana is a cool town to wander around in. Food is awful though, they have limited imports. It's a pretty big detour and the diving is allegedly not great save for Jardins de la Reine but that will require a week of your time.
2. Almost all of the cenotes you will dive are south of Playa Del Carmen, as far south as Tulum. So I wouldn't stay in Cancun, plus Cancun sucks imo. Big hotels and resorts and nothing else. Might be your style though. PDC has an awesome 2km pedestrian mall down the main drag by the beach if you want to go out at night and try different restaurants. And there's resorts there too so you can get the best of both worlds. I recommend Dave at Abyss for cenotes, Canadian guy in PDC. Knows what he's doing. You could also stay around Tulum which is beautiful and quiet in an all inclusive, just check with dive ops about logistics (picks ups, etc). Unless you're renting a car. Between Playa and Tulum there's Akumal and some other little resort beach areas.
3. For Chichen Itza it doesn't matter if you're doing an organized day trip, you should be able to find tours out of either. Both are about 2hrs away. Check out Tulum as well since you're so close, also mayan ruins but smaller but on the water, very scenic. If you have people in your group that aren't diving the cenotes with you, they would probably enjoy Rio Secreto. Also some cenotes are really cool just to swim in
4. If you're going all this way and it's your first time I really think you should add a day trip to Cozumel. It's easy to do as a day trip from PDC on a calm day so you don't have to change hotel, etc.. you might as well see what it's like for a day. Ask for one of the Palancar or Columbia dives, they have nice pinnacles, I enjoyed them the most. Cozumel has lots of great restaurants as well. Though having been where you've been lower your expectations as far as sea life and soft coral is concerned
But the water can be crystal clear.