This is the sixth of a series of caches along the Chisholm Trail, a foot and cycle path connecting various parts of Cambridge, including Fen Ditton, the River Cam and Perne Road. Phase 1 of the trail was only recently completed in November 2020, with the second and final phase not being completed yet. The trail is a lovely route, including great views of the River Cam, but can get quite busy especially on sunny days. For several of the caches, I have included an image with an arrow pointing towards the direction to walk or look to arrive at the cache relatively quickly.
The sixth cache is under the mossy bark at the center of this photo (it is a bit brighter in real life):