Sizdeh-be-dar is a festival celebrated in Iran on the thirteenth day of the Persian new year, April 2nd. "Sizdeh" means thirteen in Persian, and "be-dar" means "outdoors". Therefore, the festival is also known as "Nature Day" in Iran. On Sizdeh-be-dar, people traditionally spend the day outdoors in parks, forests, or any other natural setting, having picnics with their families and friends. They typically bring food and drinks, and enjoy a day of relaxation and fun under the sun. It is believed that spending time in nature on this day brings good luck and joy for the coming year. Sizdeh-be-dar is a popular and joyful festival in Iran, which highlights the country's rich cultural traditions and its appreciation for nature and the outdoors.