JDiver

Opinion:

Cancun diving is crap diving - very used up spur and groove swept by nearly continuous current. IMO there’s better diving out of the Akumal area, on Isla Mujeres, and if course in Cozumel.

For experienced divers, I’d recommend a day of guided cenote (cavern) diving with an outfit like Aquatech - Villas de Rosa. (One can e en stay there and rent a suite with kitchen, and there are other places to stay in the vicinity.) It’s about 20 minutes from Tulum. Or, Scuba Tulum gets good recommendations for cenote diving too.

And better than Tulum might be Cobá. Actually, a day trip encompassing Cobá (first, earlier in the morning, with a look at the crocodiles in the nearby pond) and Tulúm (with nearby beach and snorkeling) might be nice.

I’d recommend checking Trip Advisor for some reviews of places to stay.