秋吉洞 (Akiyoshido) is a famous limestone cave located in Yamaguchi Prefecture, Japan. It is part of the Akiyoshidai Quasi-National Park and is known for its stunning stalactites and stalagmites. The cave stretches over 10 kilometers, with about 1 kilometer open to the public for exploration. The cave's unique geological formations have made it a popular tourist destination. Visitors can enjoy guided tours that showcase the cave's natural beauty and learn about its history and formation. Akiyoshido is also home to various underground rivers and large chambers, creating a fascinating environment for both tourists and researchers.