In the early 20th century a more than 200 km long network of narrow gauge railways stretched throughout the Börzsöny Mountains. these lines erved farm purposes, transporting timber and stone from the mountains to sawmills, railway stations on standard gauge lines and ports of the Danube river. Timber transport branch lines were built and disassembled according to the needs of logging, therefore the entire 200 km long network was never used the same time.
The Királyrét Forest Railway was built in 1893, as first of the narrow gauge lines in the Börzsöny. The originally 600 mm gauge line expanded from Kismaros to Adolf-kút loading station (today's Cseresznyefa Parking, at the end of the public road north-west from Királyrét). Originally, the main task of the railway was timber transport, it transported later stone from nearby mines as well to fulfill this new task, a new branch line had to be built. In addition to this, they built a rail connection from Kismaros to the MÁV station in Verőce, and another to the port. After the mines had been closed in 1941, the railway transported again only timber. For this sake, a new branch line to the north-east was built. Meanwhile, the railway was nationalized and assigned to the state forestry company.
The scheduled passenger traffic started in 1954 on the line Kismaros - Királyrét - Cseresznyefa - on working days, trains run from Kismaros only until Királyrét.
After 1976, the line operated as a pioneer railway. Because of the heavy traffic and the damages caused by the wet spring of 1978, the railway had to be closed. During the full reconstruction they changed the gauge to 760 mm, and disassembled the branch lines and the section Királyrét - Cseresznyefa. The works ended in 1981, and Királyrét became the new northern terminal.
New gauge needs new vehicles: the forest railway got class Mk48 diesel locomotives and passenger cars from the closed narrow gauge railway of the Hegyköz region. These locomotives are still in service, except for two: one was sold to the Austrian Zillertalbahn in the 90's, another hasn't been operational for a long time.
After the change of regime, Szokolya village decided to transact its commuter traffic with busses. Because of the decreasing traffic and the unstable economic situation, the railway line had to be closed (and reopened) several times. Finally, the situation of the railway could be stabilized until the turn of the millennium, moreover, in a few years it came to some development as well: among others, they could acquire and even build some new vehicles (see below).
Nowadays, the trains run on the 11,5 km long line between Kismaros and Királyrét. The narrow gauge railway is operated by the Börzsöny 2020 Ltd. on behalf of Ipoly Erdő Inc., and serves tourism purposes only.

Literature:
Nemoda István - Tusnádi Csaba Károly: A Börzsönyi Gyermekvasút
Website of Királyrét Forest Railway

The steam locomotive 490 2004 "Morgó" was acquired in 2003 from Szászváros (Orăştie, Romania). It was built in Reşiţa (Romania) in 1953. This loco circulates around high days and on special occasions. The special timetable can be found in advance on the website of the forest railway.
The green railcars have been built since 2003 in Paphegy, on freight car undercarriages.