From Phnom Penh, there are two routes to Kampot, National routes 2 and 3. Neither remotely matches National Rte. 4 to Sihanoukville. Both are bumpy but adequate. Rte. 3 is the more direct route, but also in slightly worse condition. The best way is to take Rte. 2 from Phnom Penh until Sambout halfway through Takeo Province. Then take a right on Road 22 that takes you the short distance onto Rte. 3 for the rest of the journey. The road from Sihanoukville is good and takes 2 hours by car.
By Bus -- Sorya Transport leaves Central market (Psar Thmei) in Phnom Penh and takes 4 to 5 hours. From Kampot buses leave from the central bus stand. The first service is at 7:30am, the last one at noon. It is a long journey since the bus has to take the long way round, making a stop at Kep, because of vehicle restrictions on bridges on the more direct routes.
There are no scheduled buses from Sihanoukville. Your guesthouse can book you a seat in a shared taxi costing $5. You can also go to the bus stand at Psar Leu, from which they depart, and negotiate the ride yourself.
By Taxi -- From or to Phnom Penh, a seat in a shared taxi costs $7 each way. Better to pay double and book the whole front seat. In Phnom Penh, the taxis leave from a stand near the InterContinental hotel. In Kampot, your guesthouse can organize one for you. Make sure that they don't organize one that is empty apart from you, or you will be driven back to the taxi stand and might have to wait awhile for it to fill up. If the guesthouse knows what they are doing, they will contact a driver who has a full taxi already but has been informed to reserve the front seat for you, hours before your departure time.
Kampot is tiny and you can walk everywhere. If you wish to explore, you can rent a motorcycle. Many decide to stay in Kampot and do Kep as a day trip since Kampot is a friendlier place to overnight, unless you actually want the evening isolation that Kep offers. The countryside around Kampot is delightful and well worth a day's two-wheel pottering, even though Bokor is off-limits. There are a couple of places near the main traffic circle that rent out bikes, Sean Ly Motor Rental Shop (No. 27 D Soeng Ngoc Rd.; tel. 012/944-687), just south of the central traffic circle, and Cheang Try (tel. 012/974-698) next door. Renting a small step-through, 100cc machine costs $5 a day. A 250cc dirt bike costs $11 to $12 a day. You can also arrange this through your guesthouse, which keeps your passport for security (instead of the rental shop). The same offices also rent cars or even four-wheel-drive vehicles for $20 per day. The dirt bikes have spent their days being plowed up to Bokor and they have suffered accordingly. Check the brakes, lights, and above all check the horn -- it is your friend.
If you don't want to drive yourself, you can take a motorbike with a driver to Kep for just $10 per day trip, or $5 one-way if you stay in Kep overnight. For more extensive tour services, contact Art Suriya Travel (tel. 012/501-742), sponsored by the owners of the Champey Inn in Kep, which offers custom tours of the surrounding area or other parts of the region. Costs are higher than the storefront tour offices, but you get the full custom treatment here. Or contact Mr. Sok Lim at his tour offices on the north end of Kampot (at riverside, north of the central bridge; tel. 012/719-872) for adventure trips and jungle-trekking tours.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.