Triangle Island
In The Wind Waker, the Triangle Isles are three islands shaped like triangles, and also in such a formation in the sea that if one were to draw lines connecting them, the result would also be a triangle. They serve the purpose of holding three statues of the goddesses, and one of three different pearls that correspond to the goddesses can be placed in their arms. This is the key to raising the Tower of the Gods that Link must enter during his quest across the Great Sea.
Eastern Triangle Island
Eastern Triangle Island has the statue of Farore, which requires that Farore's Pearl must be placed on it for activation.
Fishman's hint on Eastern Triangle Island:
Tell me, small fry... Have you ever caught a fairy before? 'Cause from what I've been told, when you've been beaten to a pulp by monsters and such, and you think you've finally met your match... If you've got a fairy with you then you've got nothing to worry about. Don't you wish you had something handy for carrying fairies around with you, fry? If you want one, go south from here until you see a miserable-looking submarine floating on the sea. Look there!
Southern Triangle Island
Southern Triangle Island has the statue of Nayru, and as such, Nayru's Pearl must be placed within its arms.
Fishman's hint on Southern Triangle Island:
A famed pictographer lives far to the north of here in Windfall Island. He's apparently real wise and talented in the ways of pictography. He's even said to have legendary pictographs that he treasures above all other things. He keeps them hidden away in a secret safe, or so they say. By the way, small fry... What exactly is a pictograph, anyway?!
Northern Triangle Island
Northern Triangle Island has the statue of Din, upon which Din's Pearl must be placed. Link can also use the Treasure Chart he received from the Six-Eye Reef to obtain the Big Octo Chart here.
Fishman's hint on Northern Triangle Island:
Let me tell you, something, small fry... The school on that Windfall Island has one gorgeous teacher! But the thing is, this gang of four little hoodlums is always causing trouble for her. Those little delinquents like to cause all sorts of trouble. They go climbing trees and hiding behind buildings instead of going to school... What a bunch of savages. Somebody's got to scold these scoundrels and set them straight for the sake of that poor teacher! You hear me, fry?
A Link to the Past Connection?
It has been noted by some members of the community that the positions of the Triangle Isles are similar to the positions of the three temples that housed the Pendants of Virtue in A Link to the Past (e.g. the Eastern Triangle Isle is similarly placed to the Eastern Palace in A Link to the Past, which held the Pendant of Courage, an attribute Farore is commonly associated with).Triangel-Insel