Difficulty: Summiteer (Level 3)
Some 500 wooden bricks were dropped into the waters of Lemvig in northwest Denmark for a project to map how rubbish moves about in the world’s seas.
The initiative hopes to identify the movements of floating plastic waste and find more effective ways to reduce it.
The pine wooden boards were chosen because they weigh about the same as the plastic that makes up around 70 per cent of marine waste in the region. The bricks will float around until they wash up on a beach or are caught in a net.
Each of them is marked with a QR code linked to the project’s homepage, where anyone who finds them will be able to register them.
They say collecting data in this way makes it possible to track rubbish and learn to prevent it from piling up.
Answer: QR codes
