Here is the full list of all 12 Iron Tides achievements.
Win a battle in two turns or less.
Win 5 battles.
Recruit a Viking through the Great Hall.
Win 15 battles.
Win 30 battles.
Recruit the maximum of 7 Vikings to crew your warship.
Complete the Wulfyr Isles questline.
Complete the Kraken's Reach questline.
Score a total of 20 critical hits.
Slay two foes in one swift strike!
Complete a total of 10 side quests.
Explore a total of 100 tiles.