Aokigahara (青木ヶ原), also known as the Suicide Forest or Sea of Trees (樹海 Jukai), is a 35-square-kilometre (14 sq mi) forest that is located at the northwest base of Mount Fuji in Japan. The forest contains a large number of rocky icy caverns, a few of which are popular tourist destinations. Aokigahara forest is very dense, shutting out all but the natural sounds of the forest itself. The forest has a historic association with "yūrei" or ghosts of the dead in Japanese mythology, and it is a notoriously common suicide site (in which 54 took place in 2010). For this reason, a sign at the head of the main trail urges suicidal visitors to think of their families and contact a suicide prevention association.