The valley here is still the Eglinton, but with each kilometre the mountains grow closer and darker. The road runs along the river, which tumbles over gravel beds in braided channels, and the forest gives way in places to wide open flats of golden tussock, where deer graze at dusk. The peaks on either side are streaked with snow for much of the year, and on a clear day their reflections shimmer in the ponds and pools beside the road.
This was once the bottom of a glacier. Ice poured down from the high country thousands of years ago and scooped out the valley into the characteristic U-shape you can see in the cross-section, with sides so steep that the forest clings to them like a tapestry. The flat floor is covered in river gravel and tussock, and the pattern of braided streams shifts each time the river floods. Rock falls and avalanches are a regular feature of this landscape, which is why the road is sometimes closed.
For riders, this section offers a restful rhythm. The surface is good, the corners are gentle, and the road follows the contours of the valley, giving long views ahead. The wind can be strong, funnelled between the mountains, and gusts can push a loaded bike sideways. Rain squalls come up the valley without warning, and the temperature can drop sharply as you gain height. Keep your speed down, partly because limits apply and partly because deer and possums and sometimes people step onto the road.
The Department of Conservation manages the area, and walking tracks lead from the road to lakes, waterfalls and viewpoints. Lake Fergus, Lake Gunn and other small lakes are surrounded by forest, and the walking tracks around them are short and easy. The Routeburn and Greenstone tracks, two of New Zealand's great walks, begin near the Divide, further on, and a few hardy trampers can be seen walking along the road with big packs.
Fuel and supplies are not available in the valley, and mobile coverage is poor. If anything goes wrong, you may have to wait for another vehicle, though the road is busy enough in summer that help is rarely far off. Carry water, a basic tool kit and warm clothing, and keep your tank topped up from Te Anau.