A passer-by alerted police after finding a pit 1.5 meters (5 feet) deep and 80 centimeters (2 1/2 feet) wide in Helden's Forest near the southern city of Venlo on Sunday.
It had been camouflaged with leaves and at the bottom were 25 steel spikes ranging from 15-30 centimeters (6-12 inches) in length, fixed in a concrete block, police spokeswoman Nicole Theun said.
"We've never seen anything like this before — I don't think anybody in the Netherlands has," Theun said. "It's out of a horror movie."
According to De Telegraaf (Dutch), a month ago a man was injured by a similar trap.
The paper quotes an expert as saying "this must be the work of a psychopath."
"This is not a joke any more _ children could fall into this," said Cees Meijer of Consumers and Safety.
Put yourself in the mind of the person(s) that did this for a minute: if he were targeting someone in particular, he had a very small chance of actually getting him or her in this way, so that can't be the aim.
If he was targeting a class of people: why? In any case it couldn't be bikers or motorcyclists, as some Dutch media have suggested, because if they rode into the pit, they'd just be thrown over the handlebars.
If it's just a joke, it has obviously gone too far.
In every scenario, it's an insane amount of work and planning to fix the spikes in concrete, lug it out there, dig a pit that deep, and then cover it up.
The chance of getting caught would be much less if he would just go shoot random people in the woods...