Issie is the sea monster Alex Stowe and his team had saved from Pirate Island. She looks like the Loch Ness monster with a horse-like head, long neck, flipper feet and humps on her back that ripples in the sea.
Issie claims that she is from another world. She is constantly searching for her foal, and has been doing so for seven hundred years. This is a possible hint that she is, in fact, the mother of the mythical Loch Ness Monster.