Phnom Penh to Koh Rong Road Trip: Top Stops & Tips

National Road 4 (NR4) connects Phnom Penh to Sihanoukville, a 226 km drive that typically takes 3.5 to 4.5 hours by car, depending on traffic and roadworks. From Sihanoukville's Serendipity Pier, high-speed ferries reach Koh Rong in about 45 minutes, making the total journey time from capital to island roughly 5 hours. The route traverses Cambodia's Central Plain before rising into the Cardamom Mountains, offering a transition from flat farmland to dense jungle hills.

For a broader perspective on planning road trips and discovering hidden gems, see how to find the best stops and hidden gems between cities.

Fuel stations are plentiful along NR4, with major brands like Caltex and Total appearing roughly every 30-40 km. As of 2025, petrol prices hover around 4,200 riel ($1.05) per liter, slightly higher than in the capital. For the round trip, budget about 80,000 riel ($20) in fuel for a standard sedan.

The road quality varies: from Phnom Penh to Kampong Speu, it's mostly four-lane divided highway in good condition. Beyond that, it narrows to two lanes with occasional potholes, especially near construction zones. In 2023, a major upgrade project began to widen the entire corridor to four lanes, with completion expected by 2026. This means intermittent delays and rough patches.

Key Logistics Facts

• National Road 4 is the only direct highway to Sihanoukville.
• There are two toll booths along the route, charging 5,000 riel ($1.25) each for cars.
• TripAdvisor and Google Maps both show the same recommended route: NR4 all the way.
• Motorcycle taxis and minibuses are common, but renting a car gives more flexibility.

The landscape transitions from the flat, agricultural Central Plain to the foothills of the Cardamom Mountains. At about km 90, you'll notice the terrain becoming steeper and greener, with rubber plantations and cashew orchards lining the road. This area receives an average of 2,000 mm of rainfall annually, making it one of Cambodia's wettest zones, which is why the vegetation is so lush.

Kirirom National Park, located 30 km off NR4 at the turnoff near Giong Trom, is a key attraction. Its pine tree forest is unique in Cambodia and offers a cool escape, with temperatures dropping to as low as 15°C compared to the plains' 35°C. There are several waterfalls and hiking trails inside.

The town of Kampong Speu, at km 60, is known for its traditional sugar palm production. You can see the trees tapped for sap, which is boiled into palm sugar and used in local desserts. Stop at a roadside stand to buy some fresh palm fruit or sugar discs.

Sihanoukville, the endpoint on the mainland, is a bustling port city with a vibrant seafood market. The ferry to Koh Rong departs multiple times daily, but the best stops between Phnom Penh and Koh Rong include the Wat Leu temple on a hill overlooking the city and the Otres Beach area for a meal before your crossing.

The markets along the way offer a glimpse into local commerce: from Kampong Speu's sugar stalls to Ream's fish sellers near the national park entrance. These are great spots to buy snacks and drinks for the ride.

Road safety on NR4 is generally acceptable, but it's not without risks. Overweight trucks, incomplete roadworks, and occasional livestock crossings are the main hazards. Drive defensively, especially at night, as street lighting is limited beyond Kampong Speu. Observe speed limits: 90 km/h for cars in rural areas, 60 km/h in towns.

For families traveling with children, there are several attractions that offer safe, engaging breaks. The Kirirom Pine Resort has a playground and a petting zoo with goats and chickens. A more structured stop is the Phnom Sruok wildlife sanctuary, known for its gibbon calls and walking trails.

If traveling with pets, note that most stops allow well-behaved pets on leashes. The Sombok Samnang Restaurant in Kirirom has outdoor seating, and the staff are accommodating. Ensure you have a harness and water bowl for your pet, as the heat can be intense.

To avoid fatigue on the drive, plan to stop every 2 hours. There are several clean rest areas, such as those near Srae Ambel, which offer decent food and coffee shops. The classic 'Coconut Bar' at the Sihanoukville ferry pier is a good spot to stretch and rehydrate before boarding.

One often overlooked hidden off-route spot is the Banteay Prei temple ruin, a small Angkor-era structure located 15 km off NR4 near the town of Phnom Penh's outer district. It sees very few visitors and offers a quiet picnic spot with ancient stonework.