Balloon

A hot-air balloon or lighter-than-air device is a form of aircraft that has successfully been constructed and used on occasion in Britannia. Twice, in  Ultima IV and  Ultima VI, the Avatar of legend has needed such a vehicle for transport to places important to the quest at hand.

First Balloon
In the wake of Lord British's cultural renaissance following the christening of Britannia, scholars at the Lycaeum were able to construct the realm's first lighter-than-air device on the sovereign's behalf; unfortunately, the balloon was stolen by thieves some time before the Stranger's arrival at the beginning of Ultima IV. Although the fate of these bandits has been lost to history, their ill-gotten cargo somehow made its way to the mouth of the dungeon Hythloth, where the Stranger eventually recovered it and made use of it in the course of retrieving the white stone of Spirituality.

This balloon had no easy means by which to navigate while aboard it, being subject to the capriciousness of the changing winds. Some well-planned applications of the  Rel Hur spell, however, would make the device far more manageable.

Second Balloon
Years later, during the Avatar's efforts to halt the human / gargoyle conflict in Ultima VI, the champion of the virtues was faced with a peculiar conundrum in attempting to reach the gargoyles' Shrine of Singularity. Due to the Gargish cultural bias toward those who had wings, the shrine had been constructed such that it could be only reached via flight.

Unfortunately, the art of ballooning had long been lost by this age, save for one lone tinker who had somehow managed to piece together the mechanics of the device on his own. By the time of the Avatar's arrival in the realm, however, this individual had left his homeland near Minoc to work under the employ of the mad mage, Sutek, and had lost his life within the insane wizard's catacombs. After the hero tracked down the unfortunate balloonist's body and found his blueprints, the Avatar was able to eventually construct a balloon, making use of the services of numerous artisans and craftspeople of the realm. Once more, navigation aboard the balloon was difficult, and the use of magic or an artifact able to change the course of the winds proved invaluable in steering it.

The Ultima 6 Project
In The Ultima 6 Project, the use of a magic fans or Wind Change spells were no longer required to steer the balloon up to the Shrine of Singularity; although, an anchor with rope was required for ballast. After reaching the Shrine, the hero was able to hang a rope down the cliff to enable a future return without the balloon's assistance. The balloon could not be used anywhere else.