Our last trip to the Osa was in 2017. We flew into Puerto Jimenez, rented a vehicle and drove to Drake Bay. It wasn't a terrible drive, slow, bumpy, lots of hills, but I was fine with it. I did overhear other people complaining about the drive, but I thought it was fine, definitely more challenging than what is considered normal in the states. If I remember correctly there were 4 river crossings. The first 3 weren't much, that last one was much more than I expected. The agent at the rental car told me how to take the crossing, but I wasn't 100% on the instructions so I pulled off to the side for a few minutes and looked it over. Fortunately a dirt bike came down the road. I watched him get about 1/3 of the way across, saw how high the water was on his tires and followed his trail/wake, LOL.