Catch a flight from Chicago O'Hare (ORD) to Daniel Oduber Quirós International Airport (LIR) in Liberia, Costa Rica. Airlines like United and American Airlines offer flights, with a flight time of roughly 5 hours.
After arriving at LIR, take a pre-booked shuttle to Nayara Gardens in the Arenal area, which takes approximately 2.5 hours, allowing you to enjoy the scenic views on the way.