The most remarkable feature of Biržai Regional Park is its karstic landscape with numerous depressions or sinkholes that are the result of the dissolution of gypsum bedrock by groundwater. Their largest numbers are found in the vicinity of Karajimiškiai and Kirkilai, and in the Tatula valley. The sinkholes are of different forms, ranging from regular shapes to quite complicated configurations. Some of them have lakes, while others are dry. The flat landscape with frequent cavities is unique also on the European scale. Over the recent years karstic processes have intensified in particular, opening new sinkholes, which swallow up not only trees but also animals and buildings.

Nature

Among the main features are three nature monuments, of which the most famous is Karvės ola (Cow’s Cave) with five caves and a small underground lake. The total number of karstis depressions in the park is estimated to be up to 8,000. The river Tatula and the Smardonė stream are also remarkable. The park boasts Lithuania’s oldest man-made water body called Lake Širvėna, dammed at the end of the 16th century.

Cultural heritage

The mound of Ąžuolpamūšė is a witness of the distant past. Biržai Castle, built in the 16th century, is the most distinct example of a bastion-type fortress in Lithuania. It is the best-preserved castle in northeastern Europe and the only of its kind in Lithuania. The Astravas estate near Biržai boasts a splendid palace built in the style of late Classicism. The interior décor of the palace, with the impressive entrance hall used for receptions and two halls, is especially valuable. After the restoration of the palace, decorative sculptures of lions made from concrete have been put at the entrance (the original sculptures are at the Military Museum in Kaunas). In 1862, a mixed park was laid out near the palace. Other remarkable features are the architectural ensemble in Pabiržė, the landscape of the Daudžgiriai and Pabiržė (Balandiškės) estates and Likėnai Park.

Museums

The castle houses a museum of regional culture, called Sėla.

Recreation

Information on the recommended sites and recreation possibilities can be obtained at the administration. Visitors who want services of a guide should book in advance. It is customary to begin all educational tours from Biržai Castle, before which tourists are advised to visit the Sėla Museum in the Radvila castle.

At Lake Gulbinas there is a beach with a shelter, picnic furniture and places for tents. The recreation areas at the karstic lakes in Kirkilai, by Karvės ola in Karajimiškis, in Užušiliai Forest and near the Ąžuolpamūšė mound are designed for short outings. Here tourists will find shelters and picnic benches.

The park is a convenient place for travellers by car, as nearly 70% of the roads are paved. There are two routes for cars: Keliaujame į žemės gelmių muziejų (Visiting the Museum of the Earth’s Crust) (2 hours, 22 km), and a 5-hour tour of the park (80 km).

Fans of active recreation have a 13 km walking or cycling trail. Here tourists can use services of a guide or travel on their own, but they should get the map and description of the route from the administration before the trip. It is a real pleasure to walk by the wooden half-kilometre long pedestrian bridge across Lake Širvėnas to the park of the Astravas estate, in which the focal point is the palace of the Tiškevičius counts. At the Ąžuolpamūšė mound visitors are to find a botanical path (1 km).

Lake Širvėnas is an excellent place for fishermen, enthusiasts of surfing and all those looking for a retreat.