If coming from Phnom Penh, note that Kep and Kampot, while relatively close, are reached by different roads. For both, Phnom Penh is left via Route 3 (which leads all the way to Kampot), but not long after the turn-off to Takeo, one needs to bear left on Route 33 which runs via Kompong Trach to reach Kep. Many buses service one town first then make their way to the second, so it's worth checking the route. Kep and Kampot are connected via the sealed Route 33a which runs not far from the coast.
Kep is easily reached from Kampot by tuk tuk ($15-$18 return, $10 one-way) and motodop ($8-$10 return, $5 one-way), with the trip taking 30-45 minutes. Daily buses run morning only, costing $3 and taking about 45 minutes. A private taxi should cost around $20 and take roughly 30 minutes each way.
A bus to Phnom Penh costs $6.50 with an alleged journey time of four hours. For a quicker trip of about 2.5 hours, a private taxi can be secured for $40. VIP minibuses don't currently service Kep, so if you want a more comfortable ride but don't want to fork out for a taxi, try transferring to Kampot to catch the Giant Ibis or Kampot Express.
Heading east to the Vietnamese border, a moto ride costs about $8, and the trip takes about an hour to 90 minutes, depending on road conditions. A tuk tuk costs $15 to $20, and will take a little longer. Bus companies also run regular daily shuttles to Ha Tien in Vietnam from where ferries leave at 10:30 and midday for Phu Quoc Island. The entire journey, from Kep to Phu Quoc, now takes just four hours. It can be arranged through your hotel or guesthouse, or through the tour companies on the market square. Make sure you have the right visa.
Boats to Koh Tonsay leave from a pier around a kilometre east of Kep Beach from 09:00 to 17:00. A roundtrip boat ticket costs $8 or you can rent the full boat for eight to 10 people for $30 one way. If you don't come in a group, expect to wait for as long as it takes for additional passengers to show up or pay the full hire price yourself. Tickets can be pre-booked at the travel agencies near the bus station, or directly at the pier.
The Crab Shuttle leaves for Kampot at 15:30 each afternoon, stopping off at Rabbit Island before arriving at Kampot at 18:00. The inward boat leaves Kampot at 09:30, arriving in Kep at 12:00. Prices are $9.50 for a one-way ticket to Kampot, and $13.50 return.
You can rent a motorbike from most guesthouses from $5 per day, expecting to spend another $2.50 on petrol. This is a nice way to have the freedom to explore some of Kep's back roads or take a day trip to Kampot.
Bicycles may come as complimentary from your guesthouse, and if you're a passionate pedal-pusher they're a great way to get about, but downhill is always more fun than getting back up.