Greenpeace is known for its direct actions and has been described as one of the most visible environmental organisations in the world. It has raised environmental issues to public knowledge, and influenced both the private and the public sector. The organization has received criticism; it was the subject of an open letter from more than 100 Nobel laureates urging Greenpeace to end its campaign against genetically modified organisms (GMOs). The organization's direct actions have sparked legal actions against Greenpeace activists, such as fines and suspended sentences for destroying a test plot of genetically modified wheat and damaging the Nazca Lines, a UN World Heritage site in Peru.