Time to reveal the answer to my mystery outing yesterday. I was here:
Glenoe Waterfall, Co Antrim
From the car park, the path leads through trees. There is a network of paths and steps, slippy and uneven in places, that meander up and down the sides of the valley to give good views of the waterfall. The land is owned by The National Trust.
This last one is for the Flickr folk!
How to get there: On the B99, 4 miles south of Larne. Bus route 170.