River crossings in Costa Rica are ubiquitous and seasonal. You’ve read in your guide-book that there aren’t always bridges. In the dry season (Dec. through April), a river crossing can be uneventful. But in the rainy season (May through Nov.), crossing the same river may vary from a pleasant adventure to a life-threatening error. Check with locals.
It doesn’t rain everyday during the green season, but when it rains, it can come hard and fast. The locals know that when the sky opens up there may be a two-hour window before the stream is impassable and they can’t get home. It all depends on how far the crossing is from the hills and how hard it’s raining.
When we come to an unfamiliar crossing, I often get out and walk the route so Steve can see how deep the water is and if there is a current. Sometimes we just wait for a local to come by, someone who is familiar with the stream, and show us the way. You should be aware that most rental cars don’t float, although I understand that ATV’s do, because of the air in the tires. But they can’t be easy to steer.
There are no river crossings between either airport and Casa Mango and Casa Papaya. Your route is paved door to door.