How about "Down in the Diving Bell?" Jeff Warner and Jeff Davis recorded it on Two Little Boys. Here's a link to the original sheet music, although Jeff and Jeff sing slightly different words and I can't read music so don't know if it's the exact same tune they use. http://levysheetmusic.mse.jhu.edu/cgi-bin/display.pl?record=054.028.000&pages=4

Once I was a sailor lad, this tale to you I'll tell
About the wonders of the deep while down in the diving bell
When I was just a sailor boy the captain challenged me
I'd not the pluck to go and see the mermaids in the sea.

Ch: Down in the diving bell to the bottom of the sea
There are the prettiest sights that you will ever see.
Down in the diving bell to the bottom of the sea
Those nice little mermaids, pretty little mermaids,
All come courting me.

When I was only halfway down the mermaids came to me
They danced around to greet me at the bottom of the sea
I clasped a mermaid in my arms, to kiss her was my wish
But like an eel she slipped away, oh you cannot kiss a fish.

Her mother brought her back to me and whispered unto me
That if I would we could be married there beneath the sea.
We were married in a chapel made out of oyster shells
The parson wore his bathing gown and the cod fish rang the bells.