Dhaka, Bangladesh (CNN) -- Six-year-old Muhammed Wasim stands on the edge of a muddy river -- an old Spider-Man bag perched on his back -- as a boat plying toward him inches closer.
The boat is a classroom, and a creative solution to flooding in Bangladesh, which is buckling under the effects of global warming.
Poverty in the South Asia nation has exacerbated the crisis.
"We don't have to buy anything. We get everything free, like pens and books," Muhammed said.
Classes in boats give children access to education when floods prevent travel on land.
Melting glaciers in the Himalayas have piled on to flooding from heavy rains, leaving Bangladeshis worried that the slivers of land they call home are quietly submerging.
The United Nations estimates that by the end of the century, 18 percent of the country will disappear, leaving 30 million people displaced.
However, one charity isn't waiting for that to happen. Shidhulai Swanirvar Sangstha is building floating schools to allow children to learn despite crumbling river banks.
The boat makes its way along winding rivers in muddy villages as students wait on dock. Once the class arrives, they jump aboard -- about 30 students per teacher -- for up to four hours a day, six days a week.
In addition to floating classrooms, there are floating libraries and computers.
"Before the library come into our village, there was no knowledge of the internet and the computer," said Hasinur Rahman, a student.
The classes -- in most cases better-equipped than schools ashore -- have also reduced the commute for students.
Bitahi, 7, says without the floating classes, she'd have to walk an hour each way.
Going to school in the rainy season can be a challenge, said Madhu Sudan Karmakar, who manages 15 floating schools for the charity.
"The children cannot go to school because it is too far and the road gets really muddy," Karmakar said. "The road is completely flooded. Some people have even died trying to get along the road."
The charity also has training boats that teach villagers about climate change. It hopes to get more funding to build more boats and reach at least 180,000 students.
But as the country battles global warming, tens of millions may have to rely on floating facilities as the waters rise around them.