Sihanoukville to My Tho: Ultimate Road Trip Guide

The coastal road from Sihanoukville to My Tho is more than a shortcut across the Mekong Delta—it's a passage through Cambodia's only deep-water port region and into Vietnam's rice bowl. Established as a key trade corridor in the 20th century, this route crosses the border at Prek Chak (Kampuchea Krom) and Xa Xia, where the landscape shifts from tropical beaches to endless paddy fields.

The journey covers roughly 620 km (385 miles) and typically takes 9–11 hours by car, depending on border crossing times and ferry schedules. Dominating the drive is National Highway 4 (NH4) in Cambodia, linking Sihanoukville to Phnom Penh, then continuing on Vietnamese National Route QL1A southward to My Tho.

Road quality varies dramatically: NH4 is well-paved with moderate traffic, while QL1A is often congested with trucks and buses. Both countries mandate seatbelts and prohibit phone use while driving—fines are enforced. For families, a practical stop is the Temple of Angkor Wat in Siem Reap, a UNESCO World Heritage site, which is a 6-hour detour north from Phnom Penh if you have extra days. For child-friendly breaks, the Sre Ambel riverboat station offers a safe boat ride excursion suitable for all ages.

Pet-friendly accommodation is available at Phnom Penh's Sokha Hotel and Ben Thanh Hotel in My Tho, both allowing dogs under 15 kg with prior notice. To manage fatigue, plan rest stops every 2 hours—notable ones include the Kampot rest stop (Km 147 on NH4) and the Cai Lay rest area (Km 2098 on QL1A) in Vietnam, both with clean restrooms and local snacks. For a unique off-route experience, consider the Kampot pepper farms, which offer tours and tastings, only 30 minutes south of the main highway.

This route passes through the Cardamom Mountains on the Cambodian side, which are part of the Greater Mekong Subregion's biodiversity hotspot. As you descend towards the coast, you'll enter the Mekong Delta's intricate network of canals, where floating markets like Cai Be, just north of My Tho, operate from dawn to mid-morning. Keep an eye out for the UNESCO-listed Phong Nha Ke Bang National Park, which, while off-route, is reachable via a detour at Dong Ha, about 200 km north—a worthwhile add-on for avid trekkers.

Climatically, the best months to drive are from November to February, when the monsoon has passed, leaving dry, sunny roads and lower humidity. In contrast, the rainy season (May to October) can cause flooding on low-lying stretches, particularly near the border. For a deeper guide on spotting hidden attractions, see how to find the best stops and hidden gems between cities.

Before setting out, note that Cambodia uses the right-hand side of the road with a speed limit of 90 km/h on highways, while Vietnam similarly drives on the right with limits varying from 60–80 km/h on QL1A. Border procedures average 30–60 minutes each way; ensure your vehicle insurance and ownership papers are ready for inspection.

Fuel stations are sparse between Sihanoukville and Phnom Penh, so fill your tank in Sihanoukville. As of mid-2024, gasoline costs approximately 4,100 Riel per liter (about $1.00) in Cambodia and 24,000 VND per liter (about $1.00) in Vietnam—budget for 620 km at 10 L/100 km, totaling around $60–$70 for fuel alone.

• Road tolls: Vietnam charges a toll on QL1A near My Tho, approximately 40,000 VND ($1.70) for sedans.
• Currency: Cambodia uses the Riel (though dollars are widely accepted); Vietnam exclusively uses the Dong.
• The Mekong River crossing at My Tho is served by a modern bridge, completed in 2018, eliminating any ferry wait.