An interesting but relatively easy trip is Scoska Cave, about halfway between Litton and Arncliffe on the south side of Littondale.
It's large, imposing entrance is in Scoska Wood about 230 feet (70m) above the River Skirfare at the head of Gildersbank Sike.
Nearby and hydrologically connected to Scoska is Bown Scar Cave, a more challenging trip.
Here are some pictures of Scoska Cave:
Entrance to Scoska Cave Inside the entrance passge
The roomy entrance passge White flowstone formation
Right Hand Series in Scoska Cave