If you're there for a while then transport around the country is easy via the coach network, but you'll want to base yourself somewhere near San Jose, as most of the buses run via the capital.
As for places to vist, La Fortuna is great for ziplining and volcano watching. Turrialba is the centre for whitewater rafting, Manuel Antonio for beaches and wildlife spotting, Puerto Viejo de Sarapiquí for river cruises, Montezuma for beaches and watersport.
Depending on your interests, you'll want to visit in dry season for beaches and sports, and the wet season for rafting. over 8 years ago
November to April (May?) is best in my opinion. The week before Easter all the locals travel and make everything busy, the week after is very quiet (three Easter trips experience). It's also busy at the Chistmas holidays with locals but not as bad.
April is probably my favorite, but it's HOT. almost 8 years ago
We traveled in July. Though technically the "rainy" season, we only experienced showers in the late afternoon & very early morning, leaving plenty of time for actvities. (The rain was actually very nice) We noticed that our trip was MUCH more affordable than similar trips during the High Season! Arenal is definitely a must see!! It's beautiful with lots of activity options!! over 7 years ago