Here is the full list of all 29 King of Seas achievements.
Fish successfully 50 times
Find 5 sunken treasures
Sink all Sovereign Pirates
Complete the world's map for the first time
Fish successfully 30 times
Reach the maximum level
Conquer 10 enemy settlements
Sink 100 ships
Conquer 5 enemy settlements
Boost a settlement completely
Earn 500.000 gold
Sink 50 ships
Fish successfully 10 times
Earn 100.000 gold from trade
Commerce every kind of resource for the first time
Earn 10.000 gold from trade
Sink 10 ships
Earn 1.000 gold from trade
Complete your first game
Complete the game in Ship's boy difficulty
Complete the game in Gunner difficulty
Complete the game in Captain difficulty
Complete the game in Corsair difficulty
Complete the game in King of Seas difficulty
Complete 30 side quests
Find 10 sunken treasures
Find 30 sunken treasures
Conquer 30 enemy settlements
Find every kind of fish for the first time