At the head of Turnagain Arm the character of the road changes. The fjord ends in broad mudflats, the mountains close in, and the highway turns south into the valley that leads towards the Kenai Peninsula. This area is the Portage valley, one of the most glaciated corners of southern Alaska, and the great ice fields of the Chugach and Kenai ranges are close at hand. Glaciers hang in the high cirques and the meltwater turns every stream the colour of milk.
The 1964 earthquake dropped this ground by several feet, and the sea flooded in and killed the forest. The grey stumps of the so-called ghost forest remain in places along the flats, still standing in the salt mud decades later. It is a sobering sight and one of the best illustrations of how violent that event was.
A side road leads to Portage Glacier and the visitor centre, and another to the tunnel at Whittier, which is a shared road and rail tube nearly four kilometres long, with timed openings and a toll. That tunnel is a remarkable piece of engineering that gives access to a port on Prince William Sound, but it is a commitment, with set schedules, so check the times if you plan to go.
Riding here is easy and fast, with wide road, gentle curves and good surface, but the weather is wilful. Wind off the ice can blow hard across the flats, and showers arrive without warning. The best light is in the long evenings of summer, when the mountains glow and the mudflats shine. Watch for wildlife: moose graze on the willow, and bald eagles perch on the dead snags. Keep your speed reasonable, because a collision with a moose is no joke, and stay alert for trucks and campers pulling out of viewpoints.