We visited and loved Drake Bay. Caño is great, and CRAD is a class operation. All dives are out at the island, as far as I know. The dives were easily within recreational limits. Visibility was sometimes 30-40’ or so; currents were easily manageable. We had good dives and saw more diversity than we expected. My understanding is the northern diving is not as good, but not from personal experience. But there are resorts in the north, and it’s easy to get to, compared with some significant logistical challenges going to Drake Bay—either fly smallish planes, or drive to Sierpe and take an open boat down a wide, gorgeous river to the ocean, then out and around to land in the surf or on the beach. Drake Bay’s funky and remote, and Guanacaste is a resort area. Lifestyle choice in large part, but I think it would be easier to do training in Guanacaste; you could probably get certified there and then go down to DB for a few days if you were so inclined—it’s just a few hours.
