I dove in Puerto Morelos the last week of January. I posted a Trip Report a couple of weeks ago which is now on page 2 of the Mexico Forum. I am now really hooked on Puerto Morelos.
The diving isn't the same as Cozumel and I still love diving in Cozumel. The reefs in Cozumel seem to have larger older and beautiful coral formations and abundant sealife. There are a lot more boats and divers in Cozumel.
However, Puerto Morelos still seems to be a virgin reef, with very healthy plant life. Tons of sea fans, sea rods, ect. Smaller reef formations, but very beautiful and abundant fish and wildlife. It is also very close to cenotes, which are awesome and there is a good wreck dive also. Saw many people wind surfing also.
Puerto Morelos still seems have the culture of a small fishing village. It's not as touristy as Cozumel, has no cruise ships, but a very refreshing cultural experience. Very few dive boats and divers in the water. Not too far from PDC or Cancun if you wanted to go. I dove with an excellent operation
www.divepuertomorelos.com. The time to go is now, I'm afraid that it will soon become another Playa del Carmen (which I also like), but Puerto Morelos is more laid back, smaller, friendly and fun. They're starting to build more large resorts in the area and its going to boom.
I stayed at the Paradisus Riviera an all inclusive about 5 min away from Puerto Morelos. Next time I want to stay in town at a smaller place to experience more of the local culture.