If it's nature you're after, you don't have to go far from the major centre. Greater Poland National Park (PL: Wielkopolski Park Narodowy) is only 15km south of the centre of Poznań and is easily reached by public transport. The park consists of 14,840 hectares of protected land, although a big splash of that is taken up by lakes! There are 5 marked hiking trails with a combined length of 85 km, with 7 specifically-curated excursion routes that allow you to discover not only the natural but also cultural values of this area as well! Cyclists will be pleased to know that there are around 100 km of roads at your disposal and horse-lovers have 30 km of track (keep it at a trot and it'll last longer!).