Once there, follow the path East, leading towards a dungeon -OR- (If Tree Gnome Village (quest) is partially complete, right click "Follow" Elkoy, who is at the beginning and end of the maze, and go north east into the dungeon)
Bank everything except Glarial's Pebble and your Rope. To enter the tomb, you cannot bring combat-related items such as weapons, armour, or runes. See Glarial's Tomb for a list of items that are allowed.
Use Glarial's urn on the Chalice of Eternity, in the centre of the room. (If you attempt to take the Chalice you will be washed up down stream and will have to get the amulet back from the chest under Glarial's tombstone before being able to return to the cave).
Access to the Waterfall dungeon for combat training. You must have Glarial's amulet in your inventory to re-enter the dungeon - attempting to enter without the amulet will result in the tunnel flooding with water, you getting washed into the river, ending up on the bank and taking some damage.