Yock Island is a small isle located in the middle of Kauroy Lake near the southern Amestrian town of Dublith. It was here that Izumi Curtis sent the Elric brothers to test their abilities in preparation for apprenticeship under her. They were to survive alone on Yock for a full month without the use of their alchemy. Additionally, she tasked them with figuring out the meaning behind the phrase "All is One and One is All" by the time their month was up. Though isolated, Yock Island seems to be teeming with all sorts of wildlife such as birds, toads, snakes, rabbits and foxes.
In the 2003 anime, Yock Island was considerably larger, being made up of several large mountains. It served as the secret birthplace of Izumi's failed human transmutation, the Homunculus Wrath. For years he lived alone in the forests of Yock until finally being discovered. Eventually, the island would go on to be literally split in half by one of Izumi's attacks, destroying a large portion of it.
Yock was also host to the battle between the Elrics and Wrath, as well as being the first place they faced Juliet Douglas knowing she was a Homunculus. Supposedly, Dante's manor was located relatively close to this lake.
It is stated by Izumi Curtis that there is no violent wildlife residing on Yock Island. During Ed and Al's time there, they encounter rabbits, foxes, various insects, and fish surrounding the island. Other than that, the island is mostly deserted.