Pff. Women, amirite? One day you’re walking down the beach and you see a beautiful woman walking out of the sea, you hit it off, you get married, have a couple of kids and then BAM! Turns out she’s a seal and she’s off gallivanting with her seal buddies without even leaving a forwarding address for child support. Ain’t it always the way? Well, maybe not where you come from but in Ireland it’s practically an epidemic. The canon is full of selkie stories. Shit, if I had my druthers, every Irish exchange of marriage vows would include the sentence “And by the way, I am totally not a seal.”
Selkie stories are not exclusively Irish, of course. In fact, it’s probably more accurate to call them a Scottish tradition but you also find Selkie tales in the Faroe Islands and Iceland and despite the basic similarities (seal turns into a woman, marries a human) they run the gamut from tragic romances to horror stories. A common feature is that the Selkie has a seal-skin cloak, without which she can’t turn into a seal again. The fisherman hides the cloak from her for years, until one day their children are searching around in the attic, find the cloak and show it to her, at which point the Selkie’s all “Laters!” and makes her escape. A particularly grim version from the Faroese Island of Kalsoy has the Selkie return to her seal family, only for her human abductor to kill her husband and children in revenge. The Selkie then swears to basically kill every dude from his village until there are enough bodies to circle the entire island which she is still doing to this day. Then there are other stories where the marriage between the fisherman and Selkie is loving and consensual, but she has to to turn into a seal to save him from drowning and so can never return to live on land. The universal theme running through these stories is loss. Happiness is transient, loss is forever. Sounds like a fun cartoon to me!
To follow up the phenomenal success of Secret of Kells, director Tomm Moore basically created Song of the Sea, an to homage selkie stories and to his own childhood growing up in Ireland in the eighties. I also grew up in Ireland in the eighties, but I remember it being distinctly less magical.

“Well, apart from the whole “being transformed into a mouse” thing.”