|Size||Vast, specifics unknown|
The Northern Isles is a term applied to the dome in which The Unknown Turaga Saga takes place and the numerous islands located within, most notably the Northern Continent. Located far to the north of the Metru Nui dome, the Northern Isles remains obscured from and unknown to the main Matoran Universe.
The Northern Isles came into existence some time before the Matoran Universe; no one is entirely sure of the circumstances of its creation and present status, since it is not contained within the body of Mata Nui like the rest of the Matoran Universe. For a rather long time, it was inhabited solely by Rahi of various kinds and the Dragon Matoran. Some millennia afterwards, normal Matoran arrived from the main Matoran Universe and colonised the western shores of the Northern Continent, founding the iconic city known as Port Spirit. The Matoran quickly spread around the continent and onto the islands surrounding it; over time, the ruling body known as the Turaga High Council came into being.
Unlike most of the universe, the Northern Isles are relatively peaceful, having suffered only a small number of disasters compared to other lands. Indeed, the biggest known conflict in the dome thus far is that of Dracos Nui, and Turaga Dlakii's fights against the Lord of the Shadow Dragons; this conflict is very recent, having only just ended. Despite the peace, though, the Council maintains an army consisting of Matoran and Toa at all times. Of course, this is based solely on what is presently known; since basically nothing is really known about it as of yet, it is likely that there were more, especially since the Isles boast a Matoran/Toa army.
Most of the dome is covered in water. About 60% or more of the surface is covered in a protodermis sea. Another 30% or less is the Northern Continent itself, while the remaining 10% consists of the countless islands ringing the continent. A large majority of the landmasses is covered with mountains; Port Spirit, for instance, is bordered by mountains on three sides.
The dome itself actually contains three exit passages. One, obscured by the Daxian Archipelago, eventually leads to Daxia (though only one being in the entire universe knows that); the second leads to Metru Nui; this one, however, was sealed in an earthquake millennia ago. The third, an obscure exit characterised as a raging river on a 45-degree angle, leads to the surface lands, and is relatively close to Mata Nui. The Pirate Captain discovered this path some decades ago, and put it to good use transporting Turaga Dlakii's army to Mata Nui.
It appears that the obscurity of the Northern Isles has resulted in many anomalies in Matoran, some which people from other domes would considered unnatural. The most obvious of these is the existence of female Ta-Matoran and Le-Matoran, this being impossible in the rest of the world. Given this situation, it is likely that male (and female) counterparts exist for each element. Similarly, there have been many instances where Matoran of one element transform into Toa of another, the best example of this being Dlakii himself. No-one is entirely sure how this happens, other than the fact that it only happens in unusual circumstances, such as those of Lai.