You’ll find 2 major airlines providing domestic air service in Costa Rica, and both offer service to/from Tamarindo Airport (TMO).  As the article suggests, much quicker and more comfortable than driving to most destinations.  The planes are small, so seating can be limited.  Also, pay attention to baggage restrictions. 

Tico Times offers Costa Rica’s domestic flight information and other useful tips for all local travelers and foreign visitors.

Source: Domestic Flights – Costa Rica Travel Info – Tico Times