Here is a collection of songs about the sea and the ocean
May I suggest La mer by French artist Charles Trenet?
This is a classic of the Italian music industry. I don't know if this fits in, you might want to check it out though, it uses the metaphor of a sailing boat to convey the idea of waiting for your soulmate to come into your life.
song about adriatic sea
A song about the sea famous througout all ex-Yu
i forgot "sea song" by robert wyatt.
and this one is about an aquarium fish. not sure if it fits.
song about a Mermaid
Another siren story.
It's a Tim Buckley cover, but I prefer this interpretation.
Xandria — The Wind and the Ocean
maybe i have other two songs fot the list:
a seal song from scottish mitology
Don't fall asleep at the helm by Sleeping With Sirens