By far the easiest way to get to Gamboa from the airport is to have someone pick you up from the airport, or by taxi. A taxi will cost around $45 dollars for one person ($5 for each extra passenger) and take anywhere from 40 minutes to forever, depending on traffic. Make sure that you negotiate the price with the driver before getting in. If you speak reasonable Spanish, and can plan ahead, you could arganize a pickup through Manni, who lives in Gamboa ( his phone number is listed in the contacts page under Noticeboard - registered users only )
Before driving yourself you may want to read this. Up for it? read on...
Via the Corridor Sur toll road and the city
From the airport, follow the signs for Panama Centro, until you see an exit for Corridor Sur (cuota). Follow corridor sur towards Panama City (there are two tolls - $1.40 & $1.25). At the end you will find a series of poorly signposted overpasses/flyovers. Basically you want to try and stay up high and go straight. You are aiming for the Cinta Costera/Avenida Balboa, which is a long straight road that follows the coast and leads towards the Bridge of the Americas, which crosses the canal. Don't worry too much if you mess up a little, just try to head west and follow the coast. If you go across the Bridge of the Americas you have gone too far and are heading for some nice beaches. Either find somewhere to turn around or just continue to a beach and try again later. Toward the end of Avenida Balboa, look for a ramp on your left heading to an overpass that loops back across the road. The sign reads "Av de Los Martires / Av Omar Torrijos", and 99% of the traffic will be going this way. Once on the ramp take the first exit right (heading for Ave Omar Torrijos) at the bottom of the ramp try to get into the left lane, follow this road (veering left) until you reach a big underpass. This is the washing machine. You need to cross the traffic and end up exiting the washing machine heading north with the airport on your right and toward a very big El Rey sign. You will now be on the Gaillard Highway. Need fuel? Theres no gas station in Gamboa so make use of any of the stations on the right.
The El Rey is the closest supermarket to Gamboa, so it might be a good idea to get some supplies before continuing. There is also a public toilet upstairs in El Rey, which may be necessary after negotiating traffic in Panama City.
Continue north along the Gaillard Highway passing through Corozol (minisuper Corozol -opposite the gas station - has excellent fresh produce) and Clayton on your right and the Miraflores locks on your left. Continue past Pedro Miguel locks, the community of Paraiso, under the Centenario Bridge, past Summit Golf Club. Turn left immediately after the road goes under a small railroad bridge. Follow the road until you get to a single lane bridge (about 10km) with a traffic light. DO NOT proceed against the light. After crossing the bridge you will have arrived in Gamboa.
Via Tumba Muerto and the autopista Centenario
Take note of your odometer when you pull out of the Airport. Follow the signs for Panama Centro. After about 16km of horrendous traffic start looking for a car dealership on your right (I think its a KIA dealer) just after you pass it start looking for a sign that says "Patacon/Pte Centenario Autopista Panama-Arraijan". You need to turn right here. The road wll pass by the new Centenario Mall - if you need supplies the El Rey is the last supermarket before Gamboa. Follow this road (it turns into the autopista) and signs for Arraijan - the traffic "should" thin a little and begin moving at a highway type speed. Don't get sucked in to turning on to Corridor Norte - unless you want to get to Gamboa via Colon. Stay on the autopista until you approach the Centenario bridge. Exit just before the bridge (exit is signposted Paraiso) turn right at the bottom of the exit ramp. Follow the road north past the golf club as above.
Gamboa is frequented by the SACA bus. SACA buses (orange and white) leave from the transit Terminal next to Albrook mall, and can also be caught from outside the El Rey supermarket. Make sure you board the bus displying the little "Gamboa" sign, else you might end up anywhere. Buses to and from Gamboa "supposedly" run every two hours, but may or may not. HERE is the latest bus schedule. The trip to Gamboa from the city will take approximately one hour.