We flew into San Jose. Liberia is closer, but we also spent a few days at the beginning checking out the Arenal/La Fortuna area. Our schedule also dictated that we fly in and out of San Jose. There is an airport in Nosara, but it didn't look like much more than an airstrip and a small building.I can only remember seeing a few planes the whole time we were there.
From San Jose we rented a car and drove everywhere. We got a local phone company sim card for my phone, and used the waze app to navigate. This made driving very easy. Costa Rica has very little street signage and it would be very hard to get around without navigation. You can rent a GPS from the rental card company for like $15 a day, but the sim card was around $20 for 2 weeks.
I felt very safe in Costa Rica. I have never been to Jamaica, and only flew through SXM, but compared to other Caribbean destinations and Mexico, I would say Cost Rica is much safer.
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