Costa Rica offers an incredible variety of fishing. The Caribean Coast offers primarily Tarpon and Snook. There are no flats to wade-fish, and the water is relatively deep. The water can be clear out past the mouths of the rivers, or beyond the "mushroom" as its called. In the Rivers, like the Rio Colorado its very muddy and tanic. Fishing here is done from lodges or resorts, as access is very limited due to the rain forest abutting the beach. Generally, you must get to these areas via boat or plane. The plane ride from San Jose is only approx. 25 minutes.
In the mountains, or "cloud forest" area at approx. 8000 feet above sea level there is a lovely eco-lodge called Trogon. Its primarily for bird watching, but it holds a secret gem. there is a beautiful free stone steam that has a good population of Rainbow Trout. Local lore says they were introduced by the vacationing supervisors building the Panama Canal.
On the Pacific Coast, there are Roosters, Sails, and other pelagic species. Here fishing is done by hiring boats out of Marina's, and lodging is mostly via hotels. there are most assuredly some famous Lodges on this Coast, especially in the Crocodile Bay Area.
A cople pieces of advice: 1. If you are planning on taking your own tackle, interior species like the Rainbow bass, etc., are perfect for a 6wt. If you venture more towards the shores, you will definitely want bigger tackle. The Common Snook there can get huge, wuth 40 to 50 pounds not out of the question, but the more commonly caught Fat Snook run considerably smaller...say 5 to 10 pounds. I know many fishermen here tackle Tarpon with 10wt rods, but after 16 years of experience, take a 14wt. the Tarpon in CR average MUCH bigger than Florida, Belize, or most other places.
If you want, you can get more information from my website 4 Points International Fishing Home