Bohinj is a great starting point for hiking. Located in the southeast part of Triglav national park in offers a great variety of hiking trails, more than 300 km of various difficulty marked trails. Also, Mt Triglav, the highest Slovenian mountain is not far away, at the end it was first climbed by four men from Bohinj.
Before hiking make sure you inform yourself thoroughly, use proper equipment and follow the guidelines.