The answer to this question depends upon how you define north. It is pretty unclear what you meant so I am probably going to tell you some stuff you already knew.
Many shops take experienced divers north of town to Cantarel (aka Eagle Ray Alley), San Juan and Barracuda. This has historically what people meant by “going north”, but that definition has gotten blurry in recent years. All of these are located on the west side of the island. You might want to think if these as near north. This is essentially an extension of the walls south of town, but to the north. These reefs tend to have higher currents and often rougher water depending on wind direction. All of these sites can be interesting, but unless you see a bunch of eagle rays there isn’t some sort of jaw dropping difference relative to the ones down south. Note that the prevailing current essentially is taking you towards the open ocean north of Cozumel from these sites—these are not meant for inexperienced divers or for anyone that sometimes wants to come up early ahead of the group. You do not want to get a bunch of divers strung out in the open ocean. This is less of an issue at southern sites because you are in the channel between Cozumel and the mainland and will have to drift past miles of shorelines and dozens of boats —just makes finding you a lot easier (still way better if you don’t get lost in the first place ) .
What I think you are actually asking about is essentially the far north. In the past several years Aldora essentially pioneered taking clients to the farther north kind of around the island from the west side wall area where most diving is done. Obviously six decades into Cozumel diving I am sure someone had been there first , but Aldora is usually who you think of as knowing the most about these sites and going there the most frequently. I think other shops occasionally go there because Aldora has highlighted them, but they are the first name that comes to mind. I am not a client of Aldora, I will let someone else elaborate on the pros and cons of these sites (probably
@Dave Dillehay who used to own Aldora )
Lastly , I did just want to mention the shallow near north fairly close to town. I don’t think this is what you are asking about but am mentioning as an aside. I have been going to the shallow north sites fairly close to shore (not out on the wall) more frequently and have good luck with macro. Pelagic Ventures (shop I dive with ) goes there if they happen to be up there. Pepes Scuba dives up there a lot since their shop is at Coral Princess. Not as much coral as at the shallow sites down south, but I run into a lot of good macro (painted elysia, leech aglaja, Cuban aglaja, etc) along with batfish. Tend to see plenty of eels also (spotted /golden tail , sharp tail ). These aren’t that hard to find down south but frequency is usually even higher up north. For Green morays, tend to have better luck in the south. I certainly wouldn’t want to dive these sites every day , but if you happen to dive them once in a trip it can be a nice change of pace if you like smaller stuff.