The entrance to the Cave of Bats (Cueva de Río Murciélagos) lies 75 meters to the northwest of the Bat Palace. Although relatively dry in the dry season, after rainfall water can pour out through the cave mouth at a rate of 8m³/second, creating enough noise to be heard in the main plaza 500 meters away. Although the seasonal flow of water has washed away almost all archaeological remains from the cave, archaeologists consider that the Cave of Bats was of ceremonial importance to the inhabitants of Dos Pilas due to the dramatic torrent that flows through it in the wet season.