If you live in New York City you probably aren’t familiar with tech’s latest disruption to transportation infrastructure: dockless bikes. While they’re slowly popping up in localities elsewhere across the country, across the rest of the world they’ve become a significant environmental nuisance. With no designated docking spaces, the bikes, with names like Ofo and Onzo, can be picked up and put down wherever and, people being people, they’re taking the newfound freedom quite literally.

This week, a dockless bike was found in a volcano in New Zealand. Auckland’s highest natural point, Mount Eden has been dormant for some 28,000 years but that doesn’t mean it’s a suitable place to leave a bike. It’s not the first time New Zealand’s capital has found the black and yellow bikes popping up in strange places; up trees, held hostage, and one even ended up in the sea.

The concept of the bikes is similar to schemes like Citibikes. Instead of taking bikes directly from locking bays, the rear wheel is immobilized when they’re not in use, meaning when people are done riding them to work or around the block, they just dismount and discard them.

In Seattle, people have been leaving dockless bikes and electric scooters wherever they’ve last used them. The city’s Department of Transportation even had to paint designated bike parking bays to try and remind people not to leave their bike in the middle of the sidewalk, or in someone else’s doorway. In Texas, the city of Austin has begun fining companies up to $200 per bike if they don’t have a proper permit, and the bike companies operating in the city have said they’re working with the government to try and figure out a way to penalize repeat offenders.

As an opinion piece in yesterday’s Washington Post pointed out, at a time when the New York City and Washington D.C. subways are causing misery for commuters, private venture capital firms are seeing the two-wheeled light and have pumped hundreds of millions of dollars into dockless businesses.

Bike sharing has particularly rocketed in China, where mobile payment services are far more sophisticated than in the U.S. or Europe. A simple scan of a cell phone and you can hire a bike for less than 15 cents an hour. No maintenance fees, no hauling it up to your room on the 7th floor; you just pick it up and put it down as and when you please.

The bigger offender is the Chinese-owned Ofo, with over ten million bikes in operation across the world. In Shanghai alone, they’re stacked up along every sidewalk. A quick stroll down the street and you’ll find yourselves repeatedly stepping over piles of them. The problem has become so bad in China they’re now trying to reward people for good behavior, with a credit system, and penalize repeat offenders.

It’s understandable that New York City officials have been slow to implement them in the city. Back in April, 12 different companies were vying for the chance to bring their dockless businesses to compete with the overcrowded and slow subways.