The cover picture shows a beautiful Indonesian coral reef. The inset is of a millimetre-sized capsule designed to clean up oil spills from environmental waters. Such capsules move as a result of the Marangoni effect. Martin Pumera and co-workers outline cleaning of oil droplets with these self-propelled artificial capsules in their Communication on page 395 ff. They study the influence of different cleaning agents (that is, surfactants) on the removal of oil from a water/air interface.