digitalfreaknyc said:

That's really strange. I was always told it was the Olivia Newton-john song.

http://www.youtube.com/watch?v=9phn7KNp9qQ

Here's the original song. It begins just as the beach scene begins and plays for about half of the scene around up to the point where Brody makes the 'bad hat' comment where a different song can be heard (possibly the ONJ song you mentioned). Most pre-1995 releases feature an alternate song that's more guitar oriented. It sounds a bit similar to 'In The Evening' by Led Zeppelin but that song was 1979.