Airports in Costa Rica closet to Playa Negra
LIBERIA INTERNATIONAL AIRPORT
Liberia International Airport is 1 hour 30 min from Playa Negra and has many flights from the US.
SAN JOSE INTERNATIONAL AIRPORT
San Jose International Airport 4.5 drive to Playa Negra. If you dont want to take the drive you can take a connecting flight to Tamarindo which is a quick 25 min drive to Playa Negra.
This is the closet city to Playa Negra and also has rental cars available. All other amenities are available in Tamarindo and is a great place to see when travelling to Playa Negra.
Rental cars are available in San Jose, Liberia and Tamarindo. I would recommend a 4wheel drive especially during the rainy season if you are planning on visiting other cities and attractions. There arent many phones available in costa rica but some rental cars give you the option of a free cell phone to use! A good option to look into.