Hai Van means sea cloud, and from the summit the name makes perfect sense: the pass is a saddle in the Truong Son range where the mountains tumble straight into the South China Sea, and the clouds gather on the ridge like steam from a kettle. At around five hundred metres, it is not high, but it marks a real boundary. To the north, the weather tends to be cool and damp, with grey drizzle in winter, and to the south, around Da Nang, it is warmer and brighter. Locals say the pass splits the country's climate in two, and for much of the year they are right.
The road is the great motorcycle ride of central Vietnam, and it is a joy. From the Da Nang side, the old highway climbs in long, gentle bends through forest and scrub, with the bay and the peninsula of Son Tra spread below. Near the top, a café, souvenir stalls and an old stone gate and the remains of bunkers sit beside the road, with sweeping views to Lang Co in the north. The tarmac is good, the corners are medium and relaxed, and the road is wide enough for easy riding. Since the long tunnel opened in the mid-2000s, most trucks and buses use it, so the pass itself is quiet, mostly motorbikes and tour vans. Fog and rain can come in without warning, making the road slick, and early morning is the best time for clear views.
The pass has long been strategic. It was a frontier between the Viet and the Cham kingdoms, and a stone gate on the summit dates back centuries. The French built fortifications to control it, and during the Vietnam War its bunkers and watchtowers saw fighting. The old road was a lifeline for generations of travellers, and it became known to the wider world when the British television programme Top Gear filmed here in 2008 and called it one of the best coast roads in the world, which sent a wave of riders to try it for themselves.
Nature is lush and warm. The slopes are covered in tropical forest, and the sea below shifts between turquoise and slate depending on the light. The air smells of salt, wet leaves and frangipani, and on clear days you can see the long curve of the beach at Lang Co.
Buy fuel in Da Nang or Lang Co, since the pass has none. Wear a light rain jacket, bring water, and take it slowly; the road is shared with scooters, and the views are a big distraction.