Meet the locals
There are ancient spinning rides designed to look like rockets or aircraft painted in the colors of national flag carrier Air Koryo.
A water park replete with spiraling chutes lies waterless and unused.
A log flume ride, offering gloomy views of cracked concrete, is similarly dry.
"I've been to an amusement fair next to Chernobyl in the town of Pripyat that never opened because of the nuclear power plant accident in 1986," says Zwanzger. "It is unfortunate, but these fun fairs have similarities."
Zwanzger was shadowed throughout by an official North Korean "guide," a mandatory companion for all foreigners.
"Even if you wanted to ride the coaster 10 times, he would probably join you every time," he says.
While these guides usually make locals wary of talking to visitors, different rules applied at the amusement parks, he says.
"If you visit North Korea, there's no other occasion that you can get so close to locals as in the amusement parks.
"If you go to museums, you're basically alone, then you're taken to see statues and war memorials and back to your hotel, which you cannot leave on your own.
"All day long you're with tourists so you never really have the potential to exchange a smile with a local or even start a chat if you speak Korean --but that is possible in an amusement park."
But while the locals were content to be thrilled by the ups and downs of the rollercoasters, for Zwanzger, who runs thethemeparkguy.com, the biggest ride was on offer outside of the parks.
“North Korea is a time machine, a journey back to another era.”