Advancements

Sky Island has an advancement tab of its own, Sky Island: a thread through Skypiea, in the order you meet it. None gives a reward. Three of them stay hidden until you get them: they are surprises.

The way up and the Angel Islands

Advancement	How to get it
Sky Island	Ride a Knock-Up Stream up to Skypiea.
Heaven's Gate	Come to the gate at the top of the clouds.
Express Shrimp	Have your boat pulled up by the express shrimp at Heaven's Gate.
A Shell With A Power	Get a dial — any one, Sky Island's or the base mod's, however you get it.
Waver	Get a waver.
Feathered Friend	Tame a Three-Jo Bird or a Sky Dot Bird.
Up In The Air	Ride a bird you tamed.
Cloud Pet	Tame a Cloud Fox or a Giant Dog.
Weatheria	Find the floating town of the weather scientists.
Birka	Set foot on Birka, the island of Enel's birth.

The Upper Yards

Advancement	How to get it
Upper Yard	Set foot on the holy land of an Upper Yard.
Giant Jack (goal)	Climb to the top of the Giant Jack.
The Bell Rings	Ring the Golden Bell at its top.
Shandora	Find the ruins of Shandora.
City Of Gold (challenge, hidden)	Find Shandora whole and golden.
Written In Stone	Learn a priest's Ordeal from its stele.
Satori, Shura, Gedatsu, Ohm Beaten (goals)	Win each priest's Ordeal. A win in Hard counts too.
Satori, Shura, Gedatsu, Ohm Beaten Hard (challenges)	Win each priest's Ordeal in Hard.
God Beaten (challenge, hidden)	Beat Enel on the Ark Maxim.
Great Serpent (challenge, hidden)	Kill the great serpent of the Upper Yard.
Sanctuary Of God	Reach the sanctuary where Enel sits.

The way back

Advancement	How to get it
Soft Landing	Come down to the Blue Sea under a balloon octopus — one that left the sky with your boat or your ship.