Google Street View has long left the streets. Google is shooting in more and more interesting locations, from theme parks to Stonehenge. It has now added another type of exotic location to the list, natural caves in Japan but also some other man-made underground locations, like mines.
The Okubo-mabu
mine, in the Shimane Prefecture and a World Heritage site, is one such location that can now be explored in Google Maps. The second location is the Akiyoshi-do limestone
cavern, a very interesting location carved out by water.
Google probably used a custom rig for its Street View equipment in the caves, it has done so before to shoot different locations. Things like the Street View Trike probably weren't of any use in these locations. The Street View trolley, which Google developed for indoor locations probably didn't fare any better either.