Pursat's own bamboo trains - much less tourist-oriented than their Battambang cousins - stop at the train crossing 800m south of NH5 along the road to Kravanh. A three- or four-hour private excursion costs around US$10, or you can hop on with the locals; departures are most frequent in the morning.
For the best scenery, head towards Phnom Penh. One option is to get off at the village of Chheu Tom and catch a moto to Chhuk Laeng Cascades (Chroek Laeng Waterfall; one hour), situated 73km southeast of Pursat and 41km south of Krakor (on NH5 near Kompong Luong).