The Berca Mud Volcanoes are the obvious day trip from Buzău — a 25 km drive north into the sub-Carpathian hills to a geological spectacle unlike anywhere else in Romania. Allow at least half a day to visit both sites (Pâclele Mici and Pâclele Mari). The drive passes through pleasant rolling countryside and the village of Berca itself is unremarkable but friendly. Without a car you will need to take a bus to Berca and arrange a local taxi for the final stretch.
The Pietroasele wine estates lie about 30 km north-east of Buzău, in the Buzău portion of the Dealu Mare DOC wine region. Pietroasele is particularly associated with white wines — Tămâioasă Românească and Fetească Regală — and a few estates offer tastings and cellar visits. The surrounding hills are pleasant walking country in autumn.
Brașov is 130 km away over the Carpathians, reachable in about two hours by car or a direct train. It makes a natural overnight stop rather than a strict day trip, but the mountain scenery of the Buzău Passage makes the drive worthwhile on its own. If you are heading north to Suceava or south back to Bucharest, the route through Buzău is the straightforward choice.