The Suwałki Landscape Park, about halfway between Suwałki and the Lithuanian border, is a cluster of pristine lakes and rugged hills that certainly merits a detour. Covering some 63 sq km, a healthy portion of the park is either lakes (26 in all, totalling 10% of the park's area) or fine forest (another 24%). It's a perfect place for walking or cycling. The village of Smolniki, 20km north of Suwałki, is probably the most convenient base for the park.
There are three good viewpoints in the village, which allow you to enjoy some of this landscape. One of the numerous walking options is an hour's walk west to Lake Hańcza, the deepest lake in the country. With its steep shores, stony bottom and amazing crystal-clear water, it's like being up in the mountains.
Three buses make the 35-minute trip each day (10zł) between Suwałki and Smolniki. For accommodation options, enquire at the Suwałki tourist information office or contact the park office on the southern edge of the park.
One special sleeping option to consider, but only feasible if you've got your own wheels since the location is so remote, is the Jaczno guest lodge, near the tiny village of Udziejek, about 6km south of Smolniki. This place is a series of timbered mountain chalets built around a beautifully restored stone farmhouse.
The 1:50,000 map Suwalski Park Krajobrazowy (10zł) is good for exploring the area. It has all the hiking trails marked on it, and sightseeing information in English on the reverse.