A number of signs showing grid reference points around Snowdon have been damaged by vandals, North Wales Police have noted.
The force has issued an appeal for information about the acts, which it said could potentially endanger the lives of those who get lost on the mountain.
Each of the signs has a grid reference, enabling walkers who come across them and are unsure of their position to identify it on Ordnance Survey maps
Senior national park warden Dewi Davies said: "To damage them endangers the lives of others and I am very disappointed with such selfish behaviour."
The grid reference discs, which were placed on gates, fences and stiles in June, were devised by the Mountain-safe Partnership and installed by the national park authority.
Damage to signs was found at Bwlch y Moch near Crib Goch, a notoriously narrow ridge that requires scrambling skills and a head for heights to bridge.
Its highest point is 3,028 ft above sea level, listing it among the 14 peaks of Snowdonia above 3,000 ft.