(CNN) — Travel to secretive North Korea is more common than it's ever been before.

The number of people curious to see inside one of the most isolated, unfathomable and feared nations on the planet is increasing, and, compared to his predecessors, leader Kim Jong Un seems happy enough to welcome them.

To a degree.

There are strict guidelines in place governing what tourists can and can do, what they can see, and even what questions they can ask. Break with protocol, or even be suspected of doing so, and you'll pay the price. That means not disrespecting the country's past and present leaders, wandering off on your own, or trying to speak to the locals without permission.

Pyongyang used to turn into absolute mayhem during rush hour," "This picture reminds me how," says Kang Jimin , who left Pyongyang for the UK in 2005.

Chris Petersen-Clausen

"I also remember how nervous I got worrying about a power shortage and the bus stopping in the middle of the roads."

"The only time when North Koreans are staring at one place like that is when foreigners are passing by," adds Kim Jun Hyok, who left Pyongyang for South Korea in 2014.

Chris Petersen-Clausen

North Korean varsity sports team," says Han Song Chol, "Looks like these girls are in a," says Han Song Chol, who left the city in 2014 for South Korea . "They are training with sneakers instead of proper training shoes."

"There was once a time when (North Korean) female soccer players used to rock in the Asian region," says Kang Jimin. "As seen in the photo, they have no choice but to train on the asphalt or dirt schoolyards like that, instead of on a proper lawn."

Chris Petersen-Clausen

"This is an Arc of Triumph, erected to commemorate Kim Il Sung allegedly liberating Korea from the Japanese," explains Russian North Korean studies researcher, Fyodor Tertitskiy. "It may be the biggest building in honor of an event which never happened."

"Allegedly, the people of Pyongyang were expecting to see a veteran general with gray hair," says Kang Jimin about the dedication ceremony. "But the crowd was rather disappointed to see Kim Il Sung emerge, who was only in his thirties at the time and looked like a Chinese food delivery guy."

Chris Petersen-Clausen

"This is a mobile propaganda vehicle," says Han Song Chol. "Due to shortages in gasoline, there are man-powered vehicles like this. In the countryside, during the spring and fall farming seasons, the North engages in propaganda activities using vehicles like this."

Chris Petersen-Clausen

"There were once rumors that prisoners executed by the firing squad were fed to the beasts in this zoo," says Kang Jimin of the remodeled Korea Central Zoo.

"These are buildings that weren't there when I was in Pyongyang," he says of the city's new Mirae "Future Scientists" Street.

Chris Petersen-Clausen

"Back when I lived there, people used to get expelled from the city if they were caught using even an electric heater. I am certain that you will still be able to find numbers of smoke-stained windows and oblique chimneys built around Gwangbok Street."

"Owning a fridge is a sign of being rich in North Korea," says Tertitskiy. "Sometimes people buy them even if they don't have power supply!"

Chris Petersen-Clausen

"This guy is a 'Daehaksaeng gyuchaldae' or a university student disciplinary officer," says Han Song Chol.

"There are many of them in Pyongyang. They mainly target women, which is why women in Pyongyang might face some 'difficulties' in the streets. Their job is to regulate women who are wearing pants or clothes that are too colorful."

Chris Petersen-Clausen

work in the fields during rice-planting season," "When I was a student, I remember being drafted to," remembers Kang Jimin

He says the more squeamish students would "scream even at the sight of leeches" at the start but soon get used to working in the environment. "They would not be surprised to see a thick snake passing by them," he says.

Chris Petersen-Clausen

"Here we can see donju (the elite of North Korea) enjoying their time at the Mirim horse riding club," says Han Song Chol.

"It costs about 100,000 KPW an hour to ride horses. Now, that would be equivalent to a four years worth of salary of a normal worker in North Korea."

Chris Petersen-Clausen

"The man on the right is doing the greeting gesture of the Korean Children's Union: 'Hansang Junbi,' or 'always ready'," says Tertitskiy.

"This gesture and phrase was taken from the Soviet Young Pioneers."

Chris Petersen-Clausen

Pyongyang's traffic girls. Kang Jimin has fond memories of

"I remember how awesome they used to look when I was younger," he says. "Me, reaching the age of puberty at the time, would have secretly wanted her skirt to be shorter!"

Chris Petersen-Clausen

"That device on her waist is the manual traffic light remote," adds Kim Jun Hyok.

"This truck is carrying chaff to a pig farm. They are still using a truck from 1958."

Chris Petersen-Clausen