On the east side of highway Prague - Berlin, just a few kilometers before the border there is a beautiful forest for the break: Jeleni vrch near Telnice. The peak is covered with forest so it is not crucial to get there, but the area itself is nice and offers diverse nature to experience.
Białowieża is a village int the east of Poland, surrounded by Białowieża Forest - the last part of the virgin forest that once stretched across the European Plain. If you wanted to feel the original nature it is a place to go.
Do you want to try how is it to swim in a water with 24% salinity? Do you want to swim outside in October? Try the fun in Bad Wilscnack thermal spring. It is healthy too. The salinity is a bit lower then in Dead Sea, but it gives the impression. Two hours in the salty pools where just enough for us, but also the city Bad Wilscnack is nice to walk and spend some thine there. You can get to Bad Wilsnack by RE2 from Berlin, it is faster and more comfortable then with a car. Caution: Make sure to not have any scratches or better do not shave a day before. Salty water can then bring you more pain the pleasure.
