Once you get to Panama it's a different world. First you must go get stamped in. I believe it was $3 to get your stamp. Then you walk down the road to immigration. Be warned you will need documented proof of leaving the country, we used our plane itinerary and it was fine. Then you get back on the van. Panama is different from Costa Rica. Be prepared for beggars some aggressive and road blocks by the government and local authorities. The views aren't as pretty. You will be passing a lot of garbage thrown onto the side of the road and poor sanitation. Next you will stop at the public boat docks, you will be given a ticket and you wait until your name is called to board the boat. While waiting you can snack on empanadas and pickled tortoise eggs (which I'm pretty sure are illegal here in the states). They are sold by locals toting them around in coolers. Don't be surprised if you are offered drugs here as well. Once you ate on the boat you may want to shield your mouth from the water spray until you reach the ocean, since all the septic systems flow into the water. From there it's a 10 minute speed boat ride to bocas.
This is a picture of is waiting on the docks with the local food vendor.