What is this song I have stuck in my head?

[smixtro]

It sounds like an Enya song but it is performed by lots of people =/

I remember seeing the video for it and it was performed in an underwater cave looking thing.

Also I think it was used on an old advert where a kid was looking for a pearl underwater...

Any help will be greatly appreciated =D

[iwbus]

http://www.theanswerbank.co.uk/Adverts/Questio n25926.html

[smixtro]

=O That's the one...

I had a look through the other sections but didn't see it there, Thank you SO much

=D