The museum at Hellfire Pass is a moving memorial to the Allied prisoners of war who built the River Kwai railway, 12,399 of whom died in the process. Along with a film and exhibits, there's a 4½-km (3-mile) walk along a section of the railway, including the notorious Hellfire Pass, one of the most grueling sections to build. The pass got its name from the fire lanterns that flickered on the mountain walls as the men worked through the night. Many people do the walk in the early morning, before the museum opens and before it gets too hot. Allow 2½ hours round-trip for the walk. Take plenty of water and snacks; there's a small shack near the museum that sells drinks, but not much food. The pass can be busy on weekends (when an average of 500 people a day visit). Bus 8203 (two hours) makes the trip to the museum. The last bus back to Kanchanaburi is at 4 pm. The drive by car is about an hour.