Seal of the Old God Dumat is an Act 2 side quest in Dragon Age II.
Acquisition
During Act 2 in the Docks at night you will be able to enter an area called Disused Passage. There inside a red crate you will find an item called "The Seal of Dumat". Loot the item and a new quest will appear in your journal.
Walkthrough
Head over to the Hightown where you will see "Bolund the Amateur Annalist". Hand over the Seal for a reward.
Rewards
1 750 Exp.