The original Wind Waker was a fantastic game, but it wasn't without its slight annoyances. One of the more irritating features was having to change the wind direction every single time you wanted to explore a different part of the map. Thankfully, Wind Waker HD remedies this problem with the Swift Sail. The Swift Sail allows you to not only sail faster, but it also automatically directs the wind, so you won't need to whip out the Wind Waker each time.
It's important to note that the Swift Sail is only attainable after you complete the first dungeon, Dragon Roost Cavern. After that's complete, you need to head back to Windfall, but make sure it's at night, since auctions never take place during the day. You could wait it out, however, you can also perform the Song of Passing (which can be learned from Tott, pictured to the left, in Windfall on the northwestern hill). Also, make sure you have around 300 Rupees on hand.
The Swift Sail shows up in the auction house at random, which means you might have to exit and re-enter it for the sail to appear. It's also worth noting that a Heart Piece appears in the auction house as well.
Getting the hang of the auction house takes a little bit of practice, but it's not extremely hard. Essentially you have a countdown timer at which point you and others will be placing bids. If you place a bid that's 10% higher, it will stun the other bidders for 15 seconds. It's a good idea to place that bid at around the 30 second mark and then place another 10% bid on top of that one to keep stunning the others. This will ensure that you'll get the Swift Sail at around 200 – 300 Rupees.