Swansea Vale Nature Reserve is a good example of post-industrial Swansea turning rough ground back toward wildlife. Paths cross wetland, grassland, scrub, and young woodland, with birds and seasonal flowers where heavy industry once shaped the valley.
It is more local and low-key than the Gower coast, but that contrast is useful. Come for a quiet walk, especially if you are staying north or east of the centre and want green space without making a full coastal excursion.