The tune is 'The Great Silkie'. It's been haunting me ever since I realised I could use it for this challenge.

The Silkie and The Fause Mermaid

In Norroway there lived a maid
At Lyse Fjord, beside the sea
And though she was of human blood
A mermaid she'd pretend to be

In summer time, upon a rock
She'd sit for hours beside the sea
And smile and wave at boats that passed
And so she sat for summers three

The sun shone bright, the sea was calm
She sat on show, her breasts were bare
To north she'd look, then east and west
And comb her long blonde silken hair

So late one summer afternoon
She sat alone, boats there were none
A seal shuff'd up upon the rock
And lay there, basking in the sun

The seal, it spoke, and made her start
Such things in legend she had heard
But, here, on Lyse Fjord rock
She sat entranced by every word

'List to me, maid, for thou art fair
At first I thought thee silkie kind
But though I see that thou art not
I'll love thee still, as thou shalt find

'Come swim with me upon the sea
Come live with me, and be my wife
Leave this hard land, with all its toil
Enjoy the sea, where there's no strife

We'll swim far north to Arctic bliss
We'll see where icebergs new are made
Beneath the Northern Lights we'll kiss
As nature's wonders are displayed

We'll swim far south, to warmer seas
There's food a-plenty, have no fear
Then back to Ireland. Scotland, France
And Norroway again, next year"

Some say she slipped from off the rock
Some say a freak wave dragged her in
The two children she left behind
Ne'er saw their mother ere again

Now every year by Lyse Fjord
Two children sit and look to sea
And every year two seals are there
The fause mermaid and grey Silkie