i don't often recommend this place as i like to keep it to myself but on the west coast of lithuania, there is a stretch of land called the curonian spit, it is sand that has formed a thin strip of land over hundreds of years, it's about 60km length and a 1km wide, the west side of it is on the baltic coast and you get to it by walking though magnificant pine forests. the east side has lots of small fishing villages and stuff, and will probably be tourist hotspot in another 5 years, but at the moment it's tranquil as feck
you have to get a boat from klaipeda on the coast of lithuania (memel in german) to get out to the strip of land, it's a peaceful place
It also shares it's southern border with the russian enclave of kaliningrad (not the main land bit, but it also has a bit of the curonian spit), which is also worth a visit for differing reasons