Though certain Koro would be rather untenable to access, Ga-Koro is a particular brand of screwed, given its accessibility and lack of defensive measures from an amphibious assault. I guess the British (and quite possibly the vikings before them) would use or sell the matoran as slaves *interesting* things with Atlantic hurricane seasons.) (On another interesting note, the placement of the island would do. As does an alternative scenario of the island just *popping up* in 2001, with all inhabitants along for the ride (except Makuta). Even assuming the Toa or Makuta (I do not wish to consider the latter popping up, full stop) didn't make the transition, the local Rahi are more than enough to force European colonization attempts to concede 'this land is death, we cannot compete with local predators' up until, say, the mid-1800s? On the other hand, assuming the island *is* inhabited (by fauna, pre-existing villagers, etc.), travel to the landmass might be somewhat restricted for quite some time, due to the wildlife being a particular brand of very freaking dangerous. This is also not factoring in the raw resources that might be gained from the island, like wood from its rather large forested section. The immediate change in timeline that comes to mind, assuming that the island is uninhabited, is that the American War for Independence ends much differently for the Colonies than in OTL, as a European forward position in the Atlantic allows for significantly higher amounts of projected power. On a tangent, now you have me thinking about the geopolitical effects if the island of Mata Nui (sans giant robot underneath) would be planted like so in the Atlantic.

The island of mata nui