There are two major roads to get from Danang to Hai Van Pass. One of them is a coastal route and the other is an inland highway. In case you come directly from the airport you are likely to come from the inland road. However, the coastal route is infinitely more scenic.
Both roads bifurcate on to the Hai Van Pass at the same place on the northern part of the city. You can either go through the tunnel post the Song Cu De Bridge for the inland route or continue straight on the Deo Hai Van Route for the more scenic coastal route.
Both journeys stretch for approximately 25 km and take an hour to complete.