“Despite its romantic title the Hai Van Pass has always been something of a frontier,” says Vietnam Coracle: “a boundary of kingdoms and climate, often fought over, sometimes tragic but never losing its ability to inspire awe.” From the top of the pass there are “superb views, weather permitting, over the sweeping curve of Da Nang Bay, with glimpses of the rail lines looping and tunnelling along the cliff,” writes Rough Guides. “The two routes converge again where the tunnel emerges, at the small beach town of Lang Co, whose beach boasts brilliant white sands -- and is still, as yet, markedly undeveloped.”