CodMan echoed me before I even replied!
But true, he is now one of the seekers of the minute.
On SCUBABoard, we hear this question often, and about all destinations, not just Roatan.
Truth is- they will take you where they'll take you. To many of us who have seen all sides of Roatan, we really enjoy the South side, as that's where the cool micro stuff hangs out. The North and West have fine diving, but it's the same critters that you can see anywhere else in the Caribbean.
Most divers who come to Roatan always "know" that they "must see" Mary's Place... kind of like divers that go to Belize must see the Blue Hole. Don't misunderstand, I'd rather dive Mary's a hundred times rather than the Blue Hole twice, but Mary's Place is highly over rated.
It does give divers something they can see. The treasure of Roatan lies elsewhere.... just in front of you... even at the South side's Mary's Place! As CodMan intimated, the top of the reef is alive, awash with fresh currents and thriving. The huge deep crevices of Mary's Place (15 feet wide and 95+ deep) are spectacular, but devoid of most visible life.
This is essentialy the reason HowieDean is not so thrilled with the North side's Aguilla wreck- she's too deep to attract the same kind of things that a shallow South side wreck easily brings in. His favorite Spooky Channel is a great night dive!
When you go to a dive op, go with the flow. If, by midweek you have proved that you have good buoyancy and observational skills, it may well be appropriate for you to talk to the DM about other more challenging dive sites.
On other islands, when we have current dives that well surpass Cozumel, we consider the dive group as a whole, then might ask the DM quietly if we could do this or that other dive that is more of an interest. On Roatan, skill sets are not required to be all that broad- certainly there are no currents of any note on a "regular dive".
In Roatan, your DM should be judged by his ability to provide you with an understanding and sight of the little magical critters. If, when diving on the South side, if he can't show you a Seahorse on every dive, if he can't find you at least one Pipefish, several Neck Crabs... you got the wrong DM... move on!
In short: no sense in asking us for our favorite dive sites- most of the responses will be of the "popular sites", and trust me, there's a whole lot out there more interesting than Mary's Place (MP).
Case in point: After many years of going to MP with my favorite dive resort, CoCoView, I grew quickly bored with MP. There are a few other chasms and holes to poke around into that are off the regular tour. My favorite spot, right next to MP, to visit is a lengthy overhead environment "tunnel" that, no- I would not describe lest someone be tempted to risk entering unqualified.
Just go with a good DM. Go very slowly, take a glass magnifier. See what you've been missing.
EEEEEEEEE
But on a few occasions, I wish I had since I was trying to see the details on something that was just too small and couldn't identify it. But if you don't want to bother with a magnifier, you'll still have a great time like me looking at the small, but not tiny stuff! Also I had my camera so I I was busy snapping stuff right and left. We saw all kninds of neat little stuff... Seahorses, a black flamingo tongue, cleaner shrimp, tiny spotted drums (so small you could barely see them).
