My wife and I have been to Costa Rica ten of the last twelve years, she got certified there. One question is when will you be going. I have heard great things about the Bat Islands, but have never been because I am a farmer and cannot get away except in winter and you cannot get there then because of rough seas. We have been to every corner of the country and the southern part of the Pacific coast is our favorite. It is much less built up than Guanacaste with much more wildlife and it can be much more affordable.
The best diving down south is at Isla Del Cano, it is a long boat ride but worth it every time, it is by far the most reliable place we have been diving in Costa Rica for good visibility. There are some good sites near shore as well, but with some big rivers dumping into the ocean, visibilty can be poor.
There are some other fun things to do, horse back rides into Nauyaca waterfall, canopy tours, kayaking in the ocean, in the mangroves or in the river. Some hiking, lots of deserted beaches lots of wildlife including monkeys, especially if you go to Corcovado NP, scarlet macaws, toucans, sloths, even some wild cats. One of my favorite places to stay is Club Fred in Ojochal. Another cool place is Corcovado Adventures Tent Camp, it sounds expensive but it includes your meals because there is no where else to go once you are there. They offer dive trips to Cano and are at the closest point to the island. From a more settled area in Ojochal or Uvita I would recommend Mad About Diving in Uvita for a dive operation.
Unlike most people I will recommend staying away from Monteverde and Manuel Antonio NP. Both are what I consider tourist traps, they are very busy and very over priced. Another tourist trap that I feel is worth the trip is Tabacon Hotsprings. It is very busy and over priced, but a river where you can sit under a 104 degree waterfall is something not to be missed. For Tabacon I recommend staying at Arenal observatory lodge, another great place to see wildlife.
The other area that is good for diving is Guanacaste. The best diving we have done there is off of Flamingo at the Catalina Islands. We have seen all kinds of marine life there including whales and mantas, but there is very little wildlife near the beach as this is a desert area. If you go up into the mountains in Guanacaste there is a lot of fun to be had and pretty good wildlife. I would recommend Costa Rica Diving in Flamingo or El Ocotal Resort in Ocotal. Just north of Ocotal in 2002 I saw with a 35' whale shark.
For a cloud forest experience instead of Monteverde I recommend San Gerardo de doto or San Gerardo del General, both are in the mountains south of San Jose and are small and very friendly places. You can stay quite cheaply and there is a lot of hiking and a completely different set of wildlife.
The Caribbean coast is a different story. It is very rainy there and the wildlife is incredible, but with a lot of rain and very large rivers as often as not you cannot dive. We like that part of the country, but we would spend a few days on the Pacific and watch the Caribbean weather.If they have a few good days and are expecting several more it is about an eight hour drive from Uvita or Flamingo to Puerto Viejo. When you can dive there it is really good, but don't go there just to dive as you may be very disappointed. There is a guy at Playa Cocles called Finca Chica that rents some small houses that are quite nice and reasonable and there are lots of great restaurants within reasonable walking distance. Tortuguero NP is also worth the trip strictly for wildlife viewing.
Getting around Costa Rica can be challenging. There used to be almost no road signs but that has really improved over the last few years. There are now street signs at most corners in San Jose and signs directing you to most of the more popular areas for tourists. we always rent cars but there are buses running everywhere if you want to save some money. We have had very good luck renting cars from Service Car Rental and Hola both are Costa Rican companies and they are much cheaper than the international companies. We always fly into San Jose (SJO) as from New England it is about half the price of Liberia (LIR). From SJO it is about a four hour drive to either Uvita, Flamingo or Puerto Viejo. It is about 3.5 hrs to Tabacon. If you are flying into San jose and don't want to travel too far for your first night, it is about a 40 min. drive directly north up the side of Poas volcano to Poas Volcano Lodge which is very nice and is a good transition from our winter to Costa Rican summer. From LIR it is about an hour to Flamingo or about 6-7 hours to Uvita or about 8-10 hrs to Puerto Viejo.
I hope I have answered some of your questions, if you have any others, I will watch this thread, or you can PM me. Also I am hoping to take a group to Cosat Rica next winter for a trip focused on diving, but not exclusively diving. I tried it this year but could not get enough people together to make it work. If you are interested send me a Pm.
