RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Glarial's amulet
The Old School RuneScape Wiki also has an article on Glarial's amulet.

Glarial's Amulet is acquired by the player during the Waterfall Quest. This amulet allows the wearer to enter the Waterfall dungeon, and if the amulet is not worn by the player when they try to enter the dungeon, the player will be washed down the waterfall and end up near the Fishing Guild.

To find Glarial's amulet, one must search Glarial's Tomb (Waterfall Quest required). To enter the tomb, the player must also have Glarial's pebble in their inventory (acquired during the Waterfall Quest). Please note, no combat gear, weapons, or runes are allowed within the tomb.