sentences:  Víðgelmir is 1585 m long and the largest part of the cave passage is 15.8 m high and 16.5 m wide, making it by far the largest of its kind in Iceland.The cave has a wide entrance but narrows down in some places.An iron gate was installed at the first constriction in 1991 to preserve those of the delicate lava formations or speleothems which hadn't already been destroyed.