Sihanoukville, Cambodia’s main coastal gateway and the jumping-off point for Koh Rong and Koh Rong Samloem, is a well-traveled route from Phnom Penh — helped considerably by an expressway completed in recent years that’s cut travel times significantly compared to the older coastal road.
Expressway bus: the fastest option
Since Cambodia’s first expressway opened between Phnom Penh and Sihanoukville, dedicated expressway bus services now cover the route in as little as 2-2.5 hours, a dramatic improvement over the 4-5 hours the old road required. Tickets run $10-15, and multiple operators run frequent daily departures given how popular this route has become.
Standard bus and minivan
Older-route buses and shared minivans still operate for travelers whose departure point or timing doesn’t align with expressway services, typically taking 4-5 hours for $8-12 — noticeably slower than the expressway option but sometimes more flexible on departure times or pickup locations.
Private car
A private car via the expressway covers the distance in around 2 hours for $50-70 for the vehicle, worth considering for groups of 3-4 splitting the cost, or for travelers wanting a flexible departure time or the option to stop along the way.
Continuing on to the islands
Sihanoukville serves as the ferry departure point for Koh Rong and Koh Rong Samloem, so most travelers treat it as a transit stop rather than a destination in itself — buses timed to arrive with enough buffer before the last ferry departure (typically mid-afternoon) let you skip an overnight stay in Sihanoukville entirely and head straight to the islands the same day.
Booking tips for this route
Given the expressway’s popularity, booking bus tickets a day ahead during peak season (November-February) is a reasonable precaution, particularly for early morning departures timed to connect with island ferries. Your guesthouse in Phnom Penh can typically arrange this directly.
Frequently asked questions
How long does it take to get from Phnom Penh to Sihanoukville?
As little as 2-2.5 hours via the expressway bus, or 4-5 hours on the older standard bus route.
Can I go straight from Phnom Penh to Koh Rong in one day?
Yes, with an early enough departure from Phnom Penh, you can reach Sihanoukville with time to catch an afternoon ferry to Koh Rong the same day.
Is the expressway safe and comfortable?
Yes, it’s a modern divided highway that has significantly improved both the speed and comfort of this route compared to the older coastal road.
What’s the cheapest way to make this trip?
The standard bus or shared minivan at $8-12 is cheapest, though the modest extra cost of the expressway bus for a much shorter journey is worth it for most travelers.
What to do once you reach Sihanoukville
Most travelers treat Sihanoukville itself as a brief transit stop before continuing to the islands — see our guides on Koh Rong and Koh Rong Samloem (coming soon) for what to expect once you’re on the water.
Continuing your Cambodia trip from the coast
If you’re looping back through the capital later, our Phnom Penh Airport Guide and How to Get to Phnom Penh guide cover flying out or continuing onward from there.
Comparing this route to Kampot instead
If a quieter riverside town appeals more than Sihanoukville’s beach scene, our Phnom Penh to Kampot guide covers a similar-length trip to a genuinely different kind of coastal destination.
What changed with the expressway
Before the expressway opened, this route took 4-5 hours on a winding coastal road prone to traffic near Sihanoukville itself — the new route has made a same-day Phnom Penh-to-island trip realistic in a way it simply wasn’t a few years ago.
A final word on timing this leg of your trip
Given how short the expressway trip has become, there’s little reason to build in an overnight stop in Sihanoukville itself unless you specifically want to explore the mainland town — most travelers are better served heading straight for the ferry pier and onward to the islands.
Ferry connections once you reach Sihanoukville
Multiple ferry operators run between Sihanoukville’s pier and both Koh Rong and Koh Rong Samloem, with departures roughly every hour or two during daylight hours and crossing times of 30-45 minutes depending on the specific route and boat speed.
Booking your onward ferry in advance
During peak season, booking your island ferry ticket a day ahead, either online or through your Phnom Penh guesthouse, ensures you don’t arrive at the pier only to find the next available departure is hours away.
Whichever option you choose for this leg, the improved expressway has made Cambodia’s coast meaningfully more accessible from the capital than it was just a few years ago.
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