The first clue is the bus: this military-looking heavy beast is clearly built to cross difficult terrain, yet there is little clue as to what’s next as we climb the mountain roads through the extensive and orderly coffee plantations. Then, without warning, we are off the road and on to something which would resemble a river bed if it wasn’t for the steep incline – and for over 30 minutes we rock, roll and bang our way up the volcano. This is Finca El Oasis, primarily a coffee farm but these days bringing in extra cash from a zip wire trail, with eight lines heading down Volcan Baru from a…