Termina

[MagmarFire]

I don't think it'd really be an island, per se. From what the map shows, there may be land on the other side of the mountains.

But on the other hand, we don't know exactly where Termina is, so that could be your supporting argument. No one knows, but going with something works better than going with nothing.

And welcome to TDC, by the way. Great to have you. :)