I just came back and only dove in Quepos with
http://manuelantoniodivers.com The rainy season has just ended, but the rivers still have a heavy flow into the ocean that made vis less than ideal. The dive season is just starting and conditions will be inproving now that the high rain season is over.
We stayed in the south in Dominical. As you continue pass Dominical you'll see the occassional Scuba promo, but no outfitters were operating in this area. It appears that Canos Island was the place to go in the south, but we didn't have the time.
I picked up a brochure for
Poor Man's Paradise which is located in the Canos area. It look like an interesting place to stay.
Make sure you rent a 4x4 (about $10 more than a car) for travel along the Pacific. It will be money well spent. The road south, from Dominical is terrific, but I don't know how far the new road improvements go. You need 5.5 hours driving to get to Dominical from San Jose. You'll probably need another 1.5-2 to get to the Canos area, depending on the roads.
Car break/enters in CR are huge right now. DON'T LEAVE ANYTHING in an unattended car. NOTHING! The people are great, but the urge for petty theft is too great and we met quite a few people who fell victim. The big scam is causing flats in the airport area to prey on rental cars. The theives stop to "help" you and then steal a camera or purse while distracting you. Don't travel in fear, just be smart.
