I have stayed at the Omni a couple of times,it's a great place,I don't recall a dive op though,they may be partnered with Aquaworld,personally i avoid them they are large op with mass divers if you know what I mean,you'll have a better,more personalized experience by avoiding this senario
I've done about 50 dives in Cancun,it's highly underated,I even try to get over there after a week in Cozumel,Cozumel has lots of great coral structure and better deep dives 80ft.+,but for wildlife I've seen more in Cancun,maybe I'm just lucky.
I always dive with Manta Divers,it's a 15 min. bus ride from the Omni,I leave my gear there for the week,good rental gear if needed, mantadivers.com.they take out only about 6-8 divers,they have 2 small boats,much like Cozumel you back roll off the side.Mimi and John the owners are great folks from Dallas.
Having AOW experience will be helpful for some of my recommendations,but in general most trips are 2 tanks departing at 9:00 am to 50 ft. reefs.
What I like to do.
1. A cenote (cavern) trip (hotel pick up for this one) leaves about 9:00,2 tanks returns ~3:00 after a nice l late lunch in Playa,I highly recommend this,the trip of a lifetime I've dove cenotes maybe 12 times,always a treat 75 deg. ~30 ft.
2. There are 2 nice wreck dives at ~80 ft. decent current,nice penetration,good chance for eagle rays,a good challenging dive at times,best not to do this the first day out.
3. My 2 favorite reef dives are Herradura(horseshoe),and Aristos,great swimthroughs (10-20ft. coral tunnels),nice place for huge loggerhead turtles and nurse sharks(safe),morays,drums,lobster,parrots,porcupine,angels,schools of stripe grunt,at times like an aquarium of variety.both 55 ft.
4.Night dive at Chitalles,25 ft.,can be incredible,lots of lobster,octos,crab and other nocturnal creepie crawlies.
Temps are 79-83 deg. I only use a .5 mm skin at any time of year,but a 3mm full or shorty is common. At cenotes I slip on a 3mm shorty or full over my skin,free from manta.I always go buddyless and meet lots of great people as"pickup" buddies.
You'll have a great time nomatter what you decide. Have Fun!
