Lahemaa National Park
Lahemaa National Park is about 50km east of Tallinn and is a place to find some nice forests, seaside and swamps and bogs. One of the most suggested place to go there is Viru raba (Viru bog), that has 5km foottrack and watching tower.
Many forests, swamps, bogs and beaches.
Flora and fauna
The park is large and has many interesting places to go. Therefore it is hard to give one and only direction getting there.
By car. Drive from Tallinn towards Narva via Peterburi road. About 50km from Tallinn, there is a sign showing to Loksa (left). You may want to turn there as right after just taking about few hundred metres via this smaller road towards Loksa (direction north) there is the start point to Viru bog on your right. Or you may want to drive to Loksa and further on to the seaside.
Better to buy a map from any petrol station in Tallinn before you go.
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.
Viru raba (Viru bog) has 5km foottrack and watching tower.
You can also start and finish in same location if You go to tower and back or take a round trip back to start around the bog. There are good maps and information tables at the track. The track over the bog is made of wood and usually You do not need to worry about any special footwear. Sometimes there may be more water in the bog and waterproof hiking boots are recommended.
Hiking There is a number of marked trails in the park
The official Estonian tourism website provides an extensive list of options for accommodation.
You can put up tents free of charge in official "RMK" camping sites. Also there is nothing wrong with camping outside the special site, but remember not to have any fires in places that are not meant for making a fire. Putting up a tent on private land is not allowed- you should ask permission from the owner.
On a warm summer night you may want to experience the feeling of sleeping in the watching tower in Viru Bog. The tower has a roof, so there are no worries about the rain. Sometimes there may be mosquitoes here that carry no disease but are just annoying. Sunsets and sunrises in the bog are unforgetable! 
There is no settlement in the bog, bring your own water and food.
In there forest there is a great possibility of catching a tick that can carry a disease (Tick-Borne Encephalitis or ehrlichia or borreliosis). Therefore a sufficient repellent is highly suggested. Also it is recommended to wear long, light clothes and examine your body in the evening to find any ticks.
The waterholes in bog may be tricky to get out of, and even dangerous, so better not step off the track!