CINCPAC-CINCPOA Bulletin No. 136-45 / Pict84-2 Defense Installations on Iwo Jima 10 June 1945
Typical 47 mm AT gun shelter. At the far end of this shelter was an entrance to a cave and tunnel system which was more than 800 yds long and had 14 entrances. It housed two Bn CPs. (TA-183 Q)