Tottori is sixteen kilometres of sand ridges falling into the Sea of Japan, which is not a landscape anyone expects to find in Japan. The onshore wind built it and keeps rebuilding it. Uma-no-Se, the Horse's Back, is the middle of the three ridges, and from below it is simply a wall of sand with no path up it. Loose ground steals half of every step, so the climb takes longer than it looks from where you start. Then the crest arrives and the far side drops away to the sea. Rain complicates the arithmetic. Wind driving damp sand over a ridge stacks it on the sheltered side steeper than dry sand could ever hold, because the moisture pins it there. When the sun dries that face, it fails in a single sheet and slides down like a dropped curtain. Sunren, the sand curtain, and that repeated collapse is what keeps the big bowls scooped out between the ridges.
On the sheltered side the loose sand slides until it comes to rest at the steepest angle it can manage, which leaves a smooth, steep run. You strap a board on at the top and go down it, and a fall puts you on soft sand rather than hard ground. The same onshore wind makes the main ridge a tandem paragliding launch, with the whole coastline opening up underneath you. In winter a cold snap off the Sea of Japan turns the gold ridges white, the ground breaking into crusted snow one step and dry sand the next. The oasis pond in the hollow freezes over, and the summer slopes stand empty and colourless. Beside the dunes is the only indoor sand-sculpture museum in the world, rebuilt each year around a different country by carvers working in nothing but packed sand and water, no glue and no frame. And Tottori only stays bare because people keep it that way. Left alone, the invading grass takes it, so volunteers go out and pull the weeds by hand.