From the formal marking line of the Atlantic Entrance, one enters Limón Bay (Bahía Limón), a large natural harbour. The entrance runs 5.4 mi (8.7 km). It provides a deepwater port (Christóbal), with facilities like multimodal cargo exchange (to and from train) and the Colón Free Trade Zone (a free port).
A 2.0 mi (3.2 km) channel forms the approach to the locks from the Atlantic side.
The Gatun locks, a three-stage flight of locks 1.2 mi (1.9 km) long, lifts ships to the Gatun Lake level, some 87 ft (26.5 m) above sea level.
Gatun Lake, an artificial lake formed by the building of the Gatun Dam, carries vessels 15 mi (24.2 km) across the isthmus. It is the summit canal stretch, fed by the Gatun river and emptied by basic lock operations.
From the lake, the Chagres River, a natural waterway enhanced by the damming of Gatun Lake, runs about 5.3 mi (8.5 km). Here the upper Chagres river feeds the high level canal stretch.
The Gaillard cut (or Culebra cut) slices 7.8 mi (12.6 km) through the mountain ridge, crosses the continental divide and passes under the Centennial Bridge.
The single-stage Pedro Miguel lock, which is 0.87 mi (1.4 km) long, is the first part of the descent with a lift of 9.5 meters (31 ft).
The artificial Miraflores Lake, 1.1 mi (1.7 km) long, and 16.5 meters (54 ft) above sea level.
The two-stage Miraflores locks, is 1.1 mi (1.7 km) long, with a total descent of 54 ft (16.5 m) at mid-tide.
From the Miraflores locks one reaches Balboa harbour, again with multimodal exchange provision (here the railway meets the shipping route again). Nearby is Panama City.
From this harbour an entrance/exit channel leads to the Pacific Ocean (Gulf of Panama), 8.2 mi (13.2 km) from the Miraflores locks, passing under the Bridge of the Americas.
Thus, the total length of the canal is 48 mi (77.1 km).
(courtesy of Wikipedia)