Altja river in Lahemaa National Park, Estonia

Lahemaa National Park is a park in northern Estonia, 70 kilometers east from the capital Tallinn. The Gulf of Finland is to the north of the park and the Tallinn-Narva highway (E20) to the south. Its area covers 747 km2 (including 274.9 km2 of sea).
The national park, established in 1971, is one of the main tourist draws in Estonia. Several companies offer day tour packages from Tallinn, while many people drive themselves.
There are no entry fees, all the trails are free to hike. You should just remember that take nothing but photos and memories and leave nothing but footprints.
With forests covering more than 70 percent of Lahemaa, the area is rich in flora and fauna. The landscape has many raised bogs, including the 7,000-year-old Laukasoo Reserve. The park, marked by several trails, teems with wildlife, including a population of boar, red deer, wolves, bear and lynx.
Not far from the village of Altja, also within the park, is the only open-air geology museum in Estonia.
P.S. Image attribution: Margus Opp, CC BY-SA 4.0, via Wikimedia Commons