Greenpeace Day is observed worldwide every September 15 to commemorate the founding anniversary of Greenpeace, a prominent international environmental organization. The day marks the anniversary of the first Greenpeace expedition, which set sail on September 15, 1971, to protest against underground nuclear testing by the United States on Amchitka Island in Alaska. Initially established as the Don’t Make a Wave Committee in 1969, Greenpeace has grown into a network operating in over 55 countries, addressing issues such as climate change, deforestation, and overfishing. Celebrations often include tree planting, workshops on environmental activism, and family-friendly activities. While the first Greenpeace Day was celebrated in 2011 in Vancouver, the observance has since become a broader celebration of environmental activism, encouraging individuals to support ecological causes through donations, volunteering, and adopting environmentally-friendly practices.