North of Panama City, the Transístmica highway climbs out of the sprawl toward the Caribbean, following the old route across the isthmus.
This corridor has carried travellers for five centuries. The Spanish built two paved trails across the isthmus to move the silver of Peru from the Pacific to the Caribbean: the Camino Real overland to Nombre de Dios and later Portobelo, and the Camino de Cruces, which met the Chagres River at Venta de Cruces, from where boats carried goods down to the sea. Stretches of cobbled trail survive in the forest. Panamá Viejo, the original city founded in 1519 and sacked and burned during Henry Morgan's raid in 1671, lies by the sea east of today's centre, its ruined cathedral tower standing above the mudflats. Together with Portobelo and San Lorenzo on the Caribbean coast, it tells the story of an empire's treasure route.
Chagres National Park protects the watershed that makes the canal possible, since every ship that passes through the locks uses millions of litres of fresh water. The forest here is rich in birds, monkeys and butterflies, and the river is used by Emberá communities who welcome visitors by boat. Lake Alajuela, formed by the Madden Dam in the 1930s, has quiet shores and good views.
The riding is about the transition from city to jungle. The Transístmica is busy and sometimes chaotic, with buses, lorries and sudden stops, and the surface varies, so stay alert and ride defensively. Beyond the towns, the roads to the lake and into the hills are narrower and more relaxed, with curves through the forest, but they can be slippery after rain. The wet season runs roughly from May to December, with heavy afternoon storms, while the dry season from January to April brings clearer skies and stronger winds.
There are fuel stations and roadside food along the highway, as well as small shops and fondas serving rice, beans and chicken. Carry plenty of water, start early to beat the heat and traffic, and keep an eye on the clouds: when the sky turns black over the hills in the afternoon, the rain will come hard and fast.