Isalo is the end of the long southbound haul down the RN7, and the landscape changes abruptly to mark it. After the green terraces of the highlands the road enters a country of dry grass, scattered palms and then, suddenly, a sandstone massif that rises like a ruined wall out of the plain. The Isalo range is a mass of Jurassic sandstone that wind and rain have carved into canyons, buttresses and bare orange ridges, with narrow green oases hidden between them where water still runs all year.
For a motorcyclist the approach is an open, fast, rolling road, rather straight, with the sandstone appearing on the horizon long before you reach it. Along the way you pass Ranohira, a town of around six thousand people that has the last real services before the park, including fuel, which is worth knowing because the miles beyond it toward Ilakaka and Toliara are long and thin on supplies. Ilakaka itself, further on, is a sapphire boomtown that appeared in the late nineties, and has the frontier look of a place that grew in a hurry.
Walking is the right way to see the massif itself. The national park has guided trails into canyons and natural swimming pools, and the guides are compulsory and worth paying for. You may see ring-tailed lemurs in the trees near the trails, along with sifakas, and in the evening the ridge lines turn a deep red. The Bara people who live in this region have a tradition of burying their dead in rock crevices in the sandstone, so ask before photographing anything that looks like a tomb.
The weather is dry for much of the year, hot in the afternoon and cold at night, and the rains from about December to March make parts of the area muddy and the light dramatic. Dust is a nuisance on the road shoulders. When you arrive, find a place with cold water and a bed, take the helmet off and let the quiet of the rocks settle in. After a ride like the RN7, that is the right way to finish it.