The Isle of Skye is a large island off the Scottish mainland.
Skye is the site of an uncompleted Abstergo Industries facility. Isaiah, both a Templar turncoat and defector from the Instruments of the First Will, briefly used the site around 2016 to locate the final prong of the Trident of Eden.
When a Templar strike team moved in on the base, Isaiah simply used the two pieces already in his possession to compell the team to reinforce his own group of followers. By the time a second taskforce arrived, Isaiah had already relocated to Sweden.