Udin Woods, Landscape park in Municipality of Naklo, Slovenia.

Udin Woods is a contiguous forested glacial terrace in the Municipality of Naklo, bounded by the Kranj–Golnik road to the east, the old Kranj–Tržič road to the west, the A2 freeway to the south, and Mount Križe to the north. Scots pine dominates, with sessile oak, hornbeam, and beech among the deciduous trees. The conglomerate terrace, over 50 meters thick in places, contains caves, sinkholes, and springs.

The name was first attested in 1495 as Hertzogenvorsst, and in 1679–1689 as Udenwald and Hertzogforst, all meaning 'duke's forest'. Three prehistoric hilltop settlements—Arh Hillfort, Klemenc Hillfort, and Štucelj Hillfort—left visible moats and raised rings; the Romans later built a guard tower at Štucelj.

The name Udin boršt comes from the Slovene for 'duke's forest', first recorded in 1495 as Hertzogenvorsst. It is linked either to the Vojvodski grad in Spodnje Duplje or to Archduke Charles of Austria. The forest holds 12 partisan monuments from World War II, and in Spodnje Duplje visitors can see the Vogvarjeva hiša, a wooden house over 200 years old with a black kitchen and cobbler's workshop.

Several hiking and cycling trails run through the woods and connect to nearby areas for visitors exploring the region. The pathways offer different difficulty levels and allow access on foot or bicycle.

The conglomerate beneath the woods is over 50 meters thick in places, and the caves include Arneševa luknja, known to Valvasor and described in his 1689 Slava Vojvodine Kranjske as the Felsen-Grotte bei Duplach. Its spring has long supplied drinking water, and in dry weather the cave can be entered horizontally for 800 meters.