We will be staying in Tulum for 5 nights in March. My husband would like to dive one day (he is already certified ).

1) Where is the best diving in the area (Tulum v. Akumal v. Playa del Carmen v. Cozumel)?
2) Do you have a preferred dive company?

I would say Cozumel and one of the cenotes. I don't think Tulum reef is very good. Akumal only needs snorkel equipment to see the turtles and rays; the reef is also not very good (looks pretty dead) there.

Thanks. I think we'll plan on him diving in Cozumel. I don't dive - is it worth going with him to Cozumel for the day, or should I just hang out with a good book at our beach hotel in Tulum?

I would definitely do some cenote diving - incredibly unique experience! I dove with Xibalba in Tulum but it was years ago, 2010.

Thanks - I'll tell him. We'll at least do some cenote swimming/snorkeling. ("Cenote" came out as "xenotransplantation" on my iPhone LOL).

Hahaha - I've had some hilarious iPhone autocorrects but that's a new one!

He needs to contact a dive shop on Cozumel prior to going. Most boats go out early morning, so he needs to time his ferry crossing sufficiently to meet a boat or find out who might have an afternoon dive. Dive with Martin is highly rated. He can ask on SCUBA board for recommendations.

What dates in March are you going? The end of the month is better as you'll be getting closer to less Norte winds. Cozemel will be windier than the dives closer to the mainland. In my experience Cozumel is a bit crowded diving wise for my taste.
You didn't mention Puerto Morelos, a place that I like better than the others you mentioned. I can't remember the name of the dive shop that I like but it's run by expat Americans. They take out small groups and are very professional.
There are 2 dive shops only. The one I like is on the beach north of the town.

Thanks all. We're staying in Tulum but we'll have a car, so he can go wherever the diving is great (and the winds lightest). We'll be there mid-March.