Here is the full list of all 40 Shantae and the Seven Sirens achievements.
Revitalize cellular functions.
Collect all Monster Cards.
Complete the adventure as quickly as possible!
Avoid startling the Lobster Girl throughout the adventure.
Witness every magical outcome with Slimes.
Turn an enemy to an ally by helping them heal.
Shock a circus squid.
Complete the adventure with 100% completion!
Complete the adventure with 100% completion as quickly as possible!
Complete the game without any Health upgrades and all Heart Squids collected.
Open all Shock Machines.
Upgrade all magic to max.
Unearthed all secrets.
Complete the adventure!
Defeated the Empress Siren.
Deactivate all the Towers.
Defeated the fifth Siren.
Obtain all magical forms.
Unearth a buried treasure.
Complete a Ghostly Quest.
Learn all magical dances.
Defeated the fourth Siren.
Locate the sunken ship remains.
Fell for a double cross.
Open a Shock Machine.
Ascend to Armor Town.
Defeated the third Siren.
Enter the Sea Lab.
Obtain the Lucky Amulet.
Defeated the second Siren.
Have three Monster Cards equipped at once.
Use the valve.
Uncovered a possible threat.
Win the highest total in a Hula Contest.
Reach Tree Town.
Defeated the first Siren.
Took the tour!
Obtain a Monster Card.
Complete the game in Beginner or Definitive Mode.
Complete the game in Rule Breaker or Full Deck Mode.