Grid ref using memory-map is NY 36729 36693
Using google earth it's 54(deg) 43'16.30N 2(deg) 59' 02.43W
Entrance isn't filled in, but may possibly be underwater as it's right on the edge of the riverbed in the base of the rock outcrop. The entrance is often filled with flood debris, as is much of the cave. This is really not a place to be in anything other than dry and settled weather. Even in dry periods, the water from the Caldew comes in through the roof in places and is somewhat unsettling. Be aware that the Caldew has a catchment area consisting of most of the back of Blencathra and Carrock Fell and levels can rise in an alarmingly rapid manner.
Park at the side of the road approx. 100yds north of the actual Haltcliffe bridge itself, close to the entrance of what used to be the mill. The road runs right next to the river for a short distance, before the road bends sharply to the right and goes up a steep hill. Climb down to the river from the road and head downstream, keeping to the right as you head with the flow of the river. Initially the bank is made from stones encased in mesh cages which are used to help reduce bank erosion. The river swings left, but there is an oxbow on the right, 'usually' dry in summer. Follow the oxbow and after approx. 50yds the mesh cages stop and a limestone outcrop begins. After approx another 50yds, you will be in more or less in the right spot for the entrance. The way in is a slot, right at the base of the outcrop. There are usually logs/fence-posts etc. which have been washed in and around the entrance if it has not been visited for a while. There is an alternative entrance (Hammer Root Cave) which is about another 50 yards downstream and still in the base of the outcrop. This is (or was last time I looked) partially collapsed and not passable without some work. You can often hear water from the river running down this entrance.
Not suitable for fatties.