Here is the full list of all 31 Treasure Fleet achievements.
Establish a colony.
Own at least thirteen colonies.
Complete one of king's missions.
Complete 5 missions in a row.
Capture a colony in war.
Kill at least 100 land units in combat.
Build a fortress.
Have a colony with at least 40 development.
Control three gold deposits.
Have 10 missions at the same time among the natives.
Sink or capture at least 20 pirate ships.
Have the same ship survive a storm, a sea monster attack and a mutiny.
Discover El Dorado.
Find a Fountain of Youth.
Achieve a trading score of at least 200.
Accumulate a treasury of 100,000 coins.
Reveal the entire map.
Sink or capture at least 50 ships.
Capture or raze at least 30 settlements.
Degrade relations with your ruler to "angered" status without declaring independence.
Win the war of independence.
Win the war of independence before 1600.
End the game without killing a single unit in combat.
Have a unit disappear while exploring ruins.
Lose a ship due to starvation.
Reach the end of the game.
Have at least 50 tons of gold, silver or gems aboard a ship.
Sell 5000 tons of rum.
Have at least five factories.
Have a unit achieve 3-star experience.
Build at least 20 roads, mines or farms.