Fuji Wind Cave first appears to be a big hole in the ground. It's a lava tube. You need a permit to enter. That's why having a licensed guide is good.

File information
Filename:	ya416-20191112_2243.jpg
Album name:	philbert / Aokigahara Forest and Lava Tube 青木ヶ原樹海・風穴
Keywords:	yamanashi / fujikawaguchiko / aokigahara / forest
Filesize:	59 KiB
Date added:	Jan 06, 2020
Dimensions:	600 x 400 pixels
Displayed:	23 times
IPTC Copyright:	Copyright Philbert Ono PHOTOGUIDE.JP
URL:	https://photoguide.jp/pix/displayimage.php?pid=69562
Favorites:	Remove from Favorites