AC Valhalla the Seas of Fate: Here is a brief guide to finish this quest

One of the main quests in AC Valhalla is known as "The Sea of Fate" and to initiate this quest the players will need to first reach Alrekstad. After making your way to this location, talk to Sigurd in order to start the mission. He's in the house where the dice game player is sitting. You'll have to sit through a lengthy cutscene in which it's determined that you'll be travelling to England.

AC Valhalla The Seas of Fate

Go to Alrekstad and speak with Sigurd to begin this mission. He's in the house where the dice game player is sitting. You'll have to sit through a lengthy cutscene in which it's determined that you'll be travelling to England. Return to the Alrekstad docks to meet with Sigurd after this.

Here's where another cutscene can play. After that, board Sigurd's ship and take a seat where directed. Then, you'll be taken out of the Animus and put in charge of Layla, the modern-day protagonist. Simply walk around here, and when you're ready to go back in time, enter the cabin and enter the Animus. Once you get back from the past, you will have control of Eivor again and the quest will finish.

AC Valhalla Update

• YULE SEASON: RIVER RAIDS GAME MODE
  • Addition of in-game support for River Raids.
  • Prepare your Jomsviking crew for this new highly replayable mode that will take you to unexplored regions of England, which is full of raiding opportunities. New loot, rewards, and challenges will now be available.
  • The River Raids Mode is part of the Yule Season content.
    • This is free for all Assassin’s Creed® Valhalla players, and it is accessible in-game after downloading Title Update 1.1.2.
• NEW ABILITIES
  • Berserker Trap
    • This affixes a trap to your arrow, which disperses hallucinogenic powder. The trap is set off by some surrounding movement. 
  • Battle Cry
    • Eivor lets out a bloodcurdling scream in a fit of rage, gathering power and causing nearby enemies to flee in terror, interrupting their attacks.  
  • Shoulder Bash
    • Eivor uses a shoulder bash to knock enemies back and smash objects.
• NEW SKILLS
  • Assassin Carry
    • After every assassination, Eivor will automatically carry the body
  • Assassin Slide
    • This is a slide attack that will let you knock them off balance while sprinting and then sliding into the enemies.
  • Power Stroke
    • This will initiate a speed boost on the longship and will also cost stamina
  • Arrow Looter
    • Looting chance directly from archers has been increased now.
  • Fight Ready
    • Now you will be able to start a fight with an adrenaline-filled slot always.
  • Long Ship Brace
    • When you are in command of the longship, the crew will raise their shield with you. 

Image Source: Ubisoft Montreal