There is often a slight feeling of disappointment in opening a bag of crisps. The content seems so inadequate to the wide space inside the packet. When you open it, it releases nitrogen gas that goes straight into the environment. And the pleasure of eating the crisps is over soon, leaving you with an empty packet to be disposed of.

These are more or less the thoughts that have motivated a group of Korean students to express their concern in a rather creative way.

Using 160 unopened crisp bags they built a raft, on which they were able to paddle for 1.3 km down the river Han, watched by nearly 200 spectators.

In an attempt to highlight the motive of their protest one of the students says in a video: "I bought nitrogen gas, and they gave me free shacks with it".