PRIPYAT, Ukraine — The road through the forest, abandoned, is at times barely discernible, covered with the debris of fallen tree limbs, vines, leaves and moss pushing up through cracks in the crumbling asphalt.

The moss is best avoided, says our guide, Artur N. Kalmykov, a young Ukrainian who has made a hobby of coming here to the exclusion zone surrounding the nuclear reactor at Chernobyl, set aside in perpetuity after the catastrophe in 1986. It can be radioactive, having carried buried radiation to the surface as it grew.

Above all, he says, watch out for windblown dust, which could well be laced with deadly plutonium.

Despite the dangers — which are actually minimal these days, except when the wind is howling — and the risk of arrest, Mr. Kalmykov is at home here. “In Kiev my head is full,” he said. “Here I can relax. I could hang out in Kiev. But this is more interesting.”

What Mr. Kalmykov and fellow unofficial explorers of the Chernobyl zone, members of a peculiar subculture who are in their 20s and call themselves “the stalkers,” have found is more interesting still: vast tracts of clear-cutting in the ostensibly protected forest.