Here is the full list of all 17 Sea Horizon achievements.
Defeat Nephtheus in the Dungeon.
Defeat Pāpaka in the Dungeon.
Complete the story of Dylan the adventurer.
Complete the story of Lyya the wanderer.
Complete the story of Musket the explorer.
Complete the story of Mingan the shaman.
Complete the story of Shilin the priest.
Complete the adventure of Forsaken Archipelago.
Complete the adventure of East Archipelago.
Find Leafcloud the Apothecary.
Find Yanson the Artison.
Earned more than 1000 Anchors in one run.
Earned more than 10000 Anchors in total.
Find a legendary equipment.
Deal more than 100 damage in one hit.
Play 10 skills in one turn.
Gain more than 100 Block in one fight.