After your expedition to the Forsaken Fortress, you arrive on Windfall Island.
Purchase Bait and Find Rupees
If you didn't buy bait before, now is a good time to do so. Beedle's ship circles the island. Get the bait bag if you don't already have it, and remember to buy a few hyoi pears, and fill the rest of the bag with bait.
If you bother the pigs too much, you will get defeated (like with Cuccos in previous Zelda games).
Get Tingle out of Jail
Go into the door behind Tott, who is dancing by the gravestone on the northwest part of the island. Talk to Tingle if you wish, then break the pots to find the switch to open his cell. In the Gamecube version of the game, he will give you the Tingle Tuner, which you can use if you are playing on a GameCube console and have a GBA and a GBA-to-Gamecube cable. The Tingle Tuner is not usable on the Switch 2 version. In the Wii U version of the game, he gives you the Tingle Bottle, which used to be usable with the Miiverse service. Miiverse was shut down on November 7, 2017, so the Tingle Bottle can no longer be used.
After that, he will give you the chart to his island.
If you know about the gallery side-quest already, and want to complete it, be aware that in the Gamecube version of the game, you will need to use the Tingle Tuner in order to get all of the figurines, but if you get all the figurines except the one you need the Tingle Tuner for, you will still get the prize for completing the gallery. This only applies to the Gamecube version of the game.
Get the Picto Box
Go into the cell where Tingle was being held. You can get 5 rupees under the bed. Move the box to the side by standing next to it, grabbing it and moving forward or back. Crawl into the hole, then switch to first-person view by pressing up on the C-Stick (the right control stick on Switch 2) so you can avoid falling into a trap. There are trap doors that look like wooden planks on the floor. Don't crawl onto these.
The quick way through this maze is left, right, left, right, straight three times, right, straight three times, and right again.
At the end of the maze is a chest containing the Picto Box, which is required to complete the figurine gallery side-quest. Once you have that, go back through the maze into the cell, and go outside.
Buy a Sail
After you exit the jail where you freed Tingle, go left, then left again to find a ramp up to a higher level. Go up it, then through the archway, and keep to the left to go down some stairs. Behind the counter, you find a man wearing a big hood. His name is Zunari. Talk to him and agree to buy what he's selling, and you'll get your sail. (In the Wii U version of the game, he won't sell you the sail until you have freed Tingle from jail.) If you don't have enough rupees, you will need to go around town and throw pots until you get enough.
Become Lenzo's Assistant
Turn around and go back up the stairs, and when you reach the top, turn right and look for a door with a camera above it. Go inside and talk to Lenzo. Go up the stairs behind Lenzo until you reach his gallery. Go up to each picture and press A, and Lenzo will tell you about each one. After you have checked on all of the pictures, leave the building, then go back in, and agree to try to become Lenzo's assistant.
For your first task, go to the southeastern part of the island, stand on the pier by the sailor, and face the postbox. Wait for a while until a man in red walks through the arch, then get out your picto box. He'll be putting his letter in the postbox soon, so don't waste time when you zoom in. You need to be zoomed in enough to see the red guy's whole body plus the postbox. Make sure that he isn't too small in the picture. As soon as you see he has the letter in his hand, take the picture. If you're not fast enough, the letter won't be in his hand and the picture won't count. Take the picture to Lenzo and show it to him by using your picto box while in front of him.
Be sure to talk to Lenzo after he accepts your picture, to receive your second task.
Next, go into the coffee shop above Zunari's store (i.e. the store where you bought the sail), walk up the stairs, and pick up a jar. Stand as far away from the guy at the table as you can without letting anything obstruct your view, and throw the jar at him. Quickly take out the picto box and take a picture while the guy is shaking. If you don't get the picture and you run out of jars to throw, just go outside and go back in, and the jars will be there again. After you get the picture, take it to Lenzo.
Be sure to talk to Lenzo after he accepts your picture, to receive your third and final task.
The final task is tricky, but you have to do it if you want to do the figurine gallery sidequest. Go outside Lenzo's shop and you'll see a woman in an orange dress named Linda. Walk up to make those kids start circling you, but don't get too close to Linda. Get out your picto box. Set it up so that Linda will be on the left side of your picture. She should fill about 3/4ths of the frame. Now you just need to wait for a while. Eventually, a guy named Anton will walk up the path to the right of Linda. Zoom out enough so that Anton's whole body will be in the picture, and wait for him to walk past her. When Linda and Anton look at each other, make sure none of those kids is in the frame, and take the picture. Don't worry if you don't get a chance the first time, because they look at each other a second time (but you may need to zoom out to take a picture of this second time). When you have the picture, take it to Lenzo and he'll make you his assistant. In the Gamecube (and Switch 2) version, he will give you a Joy Pendant. In the Wii U version, he will give you the Deluxe Picto Box.
If you go out and back in again, you find out that Lenzo's first job for you is to get a firefly. This is only required in the Gamecube version and is one of the tasks necessary for the gallery side-quest. You can't do this task yet, but keep it in mind for later.
Play Hide and Seek with the Killer Bees
Next, you can play hide and seek with those kids who hang around in front of Lenzo's shop. To do so, go into the door near Lenzo's shop that has a chalkboard next to it, and talk to Miss Marie until she asks you to talk to the boys. Now go out and talk to the kid in the hat. Agree to their competition.
First, go to the southwest part of the island to find the bomb shop. Go around the side of the bomb shop, sidle across the ledge, and check behind the building. You will find one of the kids. Follow him, and keep doing a rolling attack toward him by pressing A repeatedly as you go toward him. Keep doing this until you can press A to talk to him. You'll have to do the same for each kid. Remember to actually catch them after they run away from their hiding places.
Next, go to the tree near the postbox and roll into it. Another kid will appear. Catch him.
After that, go behind the gravestone in the northwest part of the island to find another kid, and catch him.
Finally, go through the arch to the left of Miss Marie's school, and check behind the bush to find the last kid. Catch him.
For finding all the Killer Bees, you get a piece of heart.
Now you can get 70 rupees, but if you already have close to the maximum number of rupees (200 in the GameCube version, 500 in the Wii U version), don't do this part until later. Go in and talk to Miss Marie and she'll give you 50 rupees. Go back out. The kids will talk to you about giving Miss Marie a Joy Pendant. To find it, roll into the tree next to the bomb shop. Then go back and show it to Miss Marie (with Y, Z, or X) to get 20 rupees.
Play Battleship
There is a battleship game in the building facing Miss Marie's. Once you win, you get a piece of heart. Win again and you get treasure chart #7. If you beat the high score, you also get treasure chart #23. If you run low on rupees, see the previous section for how to get some rupees from Miss Marie if you haven't done that already.
If you go up the staircase in the courtyard and go through the door, go over to where Mila's father is walking, climb up on the rail, and drop (don't jump) down from there, there is a chest up on the auction platform with 20 rupees in it.
Leave Windfall
Now you can leave. Get in your boat and turn until you're facing the direction that the arrow behind your boat is pointing. You can cruise out of this little enclosure by holding R, which makes you automatically go forward. Press left or right on the D-stick to steer.
Before you start sailing, there are some things to keep in mind: if you see any seagulls flocking in the air on your way, avoid them. It means that there is a Big Octo in the area, but you need to avoid it, because you have no way to defeat it at this point. Also avoid funnel-shaped cyclones, which warp you to a random spot on the map. Also, if you see a narrow boat with guys in diver masks on it, talk to the head diver to receive treasure chart #34.
When you're ready to continue, set your sail to X, Y, or Z, then use the sail to start sailing. If you want to stop, press A to put the sail away. When you don't have the sail up, you can hold A to come to a complete stop.
To continue with the story, just keep going in the direction of the wind until you automatically land on Dragon Roost Island.