Dear Chgo Diver:
As a Costa Rican, very familiar with diving in the North Pacific Coast and Papagayo Gulf, I think my advice could be somewhat helpful:
Best time to visit: Costa Rica has two seasons, dry (Dec-Apr) and wet (May-Nov). Wet means realy wet, rain almost every afternoon, although the Guanacaste province, where you'll be, is usually the driest part of the country. This means that the rainy season is not that rainy there but still rainy enough to make everything look green and, to some of us, really nice. For diving, in my humble opinion is the opposite. During our dry season, it gets very windy. This usually means choppy seas and colder waters. I believe part of the colder waters during that season also coincide with colder waters from the North where you have the winter. For me, during this season, a 7mm wet suit and a hood would be perfect. Lifewise, it changes. Colder waters bring rays. Warmer waters bring white tips. Abuntant fish all year round. During the rainy season, waters are warmer and the wind goes away. That's when I actually like it. My 5 mm suit is more than enough. Even a 3 mm one would do. Now, we've been spotting a lot of spotted eagle rays in large groups.
Diving Operations: I've neved dove with Bill Beards but I hear they are very good and professional. I normally dive with Ocotal. These guys are great and know all the sites like their backyard. Most recently, I've been diving with Summer-Salt (
www.summer-salt.com) owned by a Norwegian couple. Co-owner Kristian is one of the only two PADI course directors living in Costa Rica. The other is a Costa Rican working at Ocotal. Summer Salt is a very professional yet smaller operation. Their boat is smaller that the ones Ocotal or Bill Beard use but for small groups, you get a second to none personnalized service. I love that. Besides, you get to eat delicious pastries and bakery during the dive intervals prepared by Kristian's wife. I also highly recommend Francesco Nistri of Diving Mania, who is my instructor. His operation is in San Jose, so he's more dedicated to certifying people and organizing tours from San Jose. Francesco normally uses Summer Salt for the tours. Bill Beard and Summer Salt (as well as some others) are located in Playas del Coco. Ocotal Diving is located right on the beach in Playa Ocotal.
Where to stay: Depends on your budget and whether you want to stay close to Playas del Coco or Ocotal. When I want something nice and am willing to pay more, I go to Ocotal Resort, very nice. Normally, for weekend getaways I stay at La Flor de Itabo on Playas del Coco. Very basic, yet good enough for me. I guess you can check the Instituto Costarricence de Turismo web page (Costa Rica's Tourism Board) and compare the different hotels in the area. For diving Catalinas, you can either stay in Playas del Coco/Ocotal area or you could stay in Flamigo Beach, right in front of Catalinas.
Dive spots: Catalinas is famous for mantas and in fact that's were I've spotted 6 and 5 meter wingspan Manta Rays in the past. You get to see devil rays, sharks and sometimes even bull sharks. Last weekend, when I dove there, I didnt' see big marine life, except for spotted eagle rays. Diving was nice though. Be prepared for currents.
Bat Islands: It's a 2 hour trip from Playas del Coco. People go there to see the bull sharks at "Big Scare". Last weekend I didn't see them, even though our guide and one fellow diver did see them. Still, don't be dissapointed is you don't, cause you can do what I believe is one of the most awesome spots in Costa Rica, "Black Rock". Be sure to do this spot.
Local dives: Operations in the Playas del Coco/Ocotal area call Local dives ("Buceo local") anything withing 30 minutes distance from the coast. Diving can be excellent there. That's what I do most often and I love it. Lots of marine life and surprises regardless of poor or good viz. Must do sites include "Virador", "Argentina", "Tortuga", "Monkey Head", "Sorpresa" (this one is deeper, 90+ ft).
Other spots: Some other very nice spots a bit more distant to be called local include: To the south: "Tiburones" (Sharks), "El Ancla" (The Anchor), "Fantasma" (Ghost, 90+ ft), "Penahuaste", "El Acuario" and "Punta Gorda" (one of my favorites). To the North: "Palmares" (great place).
Where to eat: If you stay in El Coco, be sure to check out local "Tico" restaurants, great for seafood: "La Guajira" (get the mashed black beans and patacones platter, mixed ceviche and the whole fried snapper, yum!). If you don't accompany that with an ice cold Imperial, it'd be a crime. "Milanes", if you like seafood soup, say for dinner, this is the place to go. Best seafood soup in the country. Also, for drinks and snacks, try "Father Rooster" on the beach in Ocotal.
Gee, now that I think about it, this is very specific of the Golfo de Papagayo area. If you stay in Flamingo or elsewhere please let me know and I could provide appropriate info.
Final word, viz. in Costa Rica's North Pacific is not great. That's the way it is. Nutrients rich waters bring plenty of marine life. For me, that's better than cristal clear waters and more predictable underwater scenery. It's a matter of personal preference. Viz. can be very good in Caño Island (south Pacific) and in our Caribbean Coast, although due to usually rough seas and currents there, there's only one diving operation that I know about, Reef Runners. Can't speak for their quality and service as I've never dove with them.
Hope this helps!
Fernando