Just around 20 minutes bike ride from the center of Tallinn there is a amazing small nature reserve called Paljassaare. North-Tallinn has 2 peninsula, one is called Kopli and other Paljassaare. It is part of the city so basically a smaal national park in the urban Tallinn!
Its basically a paradise in the concrete jungle! This peninsula is been part of Tallinn for ages. Since 18. century until 1991 Paljassaare was held under military purpose. It was not possible to visit the place for civilians. During the soviet union the north top had a barbed wire around it to protect the border (and of course to prevent that Estonians had a chance to escape from the soviet union area!).
Now days peninsula is opened for people and bikers! Nice narrow gravel roads, private beaches, some viewing platforms and lot of birds! Around 180 different species of birds going mating to the peninsula during spring time. Also some wild animals like foxes and deers have found that Paljassaare is a great place to live! If you move quietly and try to listem soma sounds you can be lucky and see some of them. Also there is a place for (hairy cows+++) who are there in the summer. Of course they have a fence around but its possible see them and enjoy the view to the penonsula.
Paljassaare also have beautiful rocky coastline to follow. During the day time and in the evening its possible to see the Stocholm and Helsinki ferries coming in to Tallinn
If you arrive to the peninsula before going to wild area there is beautiful "Katariina pier" and "Pikakari beach". Its also possible to access there with a car. There is also a free parking lot. This pier is a perfect place to see long evening sunsets and enjoy local fisher men and people!
At the beach you can really get some waves when the ships coming to Tallinn! So have some sun baths and when you spot some bigger ship going by, jump into the water!