Pienfu, or Bat Cave as it is called for the thousands of bats which once inhabited it, is a mountain cave large enough to hold 200 people.
蝙蝠洞在復興鄉最北的三民村內，據說因曾有蝙蝠棲息而得名，然現在已不復見蝙蝠蹤跡。洞內十分寬敞，能同時容納二、三百人活動。去蝙蝠洞須先經過一條小溪，溪上有許多踏腳石，供人在溪上走過。