Lang Co is a thin spit of sand between the South China Sea and a wide, still lagoon, tucked on the northern side of the Hai Van mountains, and for many riders it is the reward at the bottom of the pass. The beach runs for miles, pale and almost empty outside the summer weekends, and behind it the lagoon is dotted with fish farms, oyster stakes and stilt houses. Behind, the green mountains rise steeply, usually with a cloud lying on the ridge. The village is small, but there is fuel, and a line of seafood restaurants along the road serves crab, clams and grilled fish.
The descent from the pass to the lagoon is one of the best parts of the ride. The road drops through hairpins and long sweeps with the sea in view, and once down it becomes flat and open, running beside the beach and the railway line. The Vietnamese north-south railway, the Reunification Express, clings to the coast here, and the sight of a train curving along the shore is a famous photograph. Keep an eye on the surface after rain, since leaves and mud can lie on the bends.
The tunnel under the pass, opened in 2005 and about six kilometres long, comes out near Lang Co, and its mouth is visible from the lagoon. The area has long been a fishing community, and in the old days it was a stop on the imperial road between Hue and Da Nang. Many travellers spend a night here, enjoying the quiet.
Food is simple and excellent. Try a plate of steamed clams with lemongrass, or a bowl of the local noodles, then a coffee on a hammock by the beach. Afternoon storms roll in from the sea in autumn, so check the sky. In summer, the beach is hot and the sea warm, and in winter, the north wind brings grey skies and cool days. Spring is the most pleasant season.