Where it sits
Kandal means “central”, and the province surrounds Phnom Penh on every side, following the Mekong and Bassac out from the capital. Its administrative seat is Ta Khmau, effectively a southern suburb of the city.
Because everything in it is within an hour of Phnom Penh, Kandal is the natural day-trip province — and it is startlingly rural the moment you leave the ring road.
Oudong
Oudong was the royal capital of Cambodia from 1618 until the court moved to Phnom Penh in 1866. The hill carries a line of stupas holding the remains of several kings, reached by a long staircase, with views out over the plain.
It was badly damaged during the conflict years and has been substantially restored. It remains an important pilgrimage site, busiest at weekends and on Buddhist holy days.
The silk islands
Koh Dach — usually called Silk Island — sits in the Mekong a short ferry ride north-east of the capital. Weaving families still work handlooms in the villages, and the island is flat, quiet and ideal for a slow cycle.
It has become the standard half-day escape from Phnom Penh, and deserves the reputation: sandy riverbanks, fruit trees, and almost no traffic.
Practicalities
Almost everything in Kandal is done as a day trip from Phnom Penh. Accommodation within the province is limited, and there is little reason to seek it out when the capital is thirty minutes away.