Hollingworth Lake is Rochdale's classic fresh-air outing: a broad reservoir at the edge of the Pennines, with a straightforward circuit, sailing activity and views that open toward the surrounding hills. It has enough facilities to be easy, but still feels like a proper change of scene from the town centre.
The lakeside path is the main draw, particularly if you want a low-effort walk with water, moorland weather and a few places for a drink afterwards. It is also a useful base for longer rambles into the South Pennine landscape.