A soarwing is a hang-glider-like device featured in Golden Sun: Dark Dawn.
Soarwings were invented by Ivan, one of the Warriors of Vale. Powered by Psynergy, this device allows its wearer to fly along the winds. However, the actual act of using one is a difficult task, even for Wind Adepts, who can normally control the wind. Thus an Adept must receive special training in the Soarwing's usage. Most of the materials used in its construction are common, save for the most critical part - the feathers of a Mountain Roc, which is so rare as to be legendary.
The soarwing was invented in the ensuing years between the Golden Sun event and the beginning of Dark Dawn. During this time, the soarwing becomes a critical element in Isaac and Garet's self-imposed duty to monitor what remains of Mount Aleph - as the landscape surrounding Mount Aleph is now impassable on foot, the only way the mountain and what remains of Sol Sanctum within can be accessed is by air.
The story of Dark Dawn is kicked off when Tyrell selfishly flies around in the only soarwing at the Lookout Cabin, despite Isaac, Garet, Matthew, and Karis' objections that he has not received proper operating instructions and training yet. When it becomes evident that Tyrell is going down, they tell him to land near the Abandoned Mine so that they can retrieve him. The soarwing is destroyed upon landing, but Tyrell is uninjured.
Later, Isaac explains that as it is necessary for him and Garet to have a soarwing at his cabin, they need a new Mountain Roc's feather so that Ivan can complete a new one. The known location of Mountain Rocs lies across the continent, however, but Isaac tasks Tyrell, Matthew, and Karis to go out on a trip across the continent to fetch one, treating this as an important rite of passage for the three to undertake as Adepts.