"Orinoco Flow" was the final track written for the album, but it was one that Enya recalled was difficult to work on, which involved several breaks from recording before coming back to it several weeks after. She later pointed out the absence of deadlines to complete the album, as granted in her contract with Warner, which allowed the song to be developed over a period of time until "we were able at the end to listen to it and say 'this is good'". It originated from a riff she had developed after Nicky suggested playing a melody in five octaves; they left the arrangement as it was, until they realised the album needed one more track. The song developed around the initial riff, itself becoming part of the chorus hook. An earlier version of the song contained no middle eight and had the line "Sail away..." after every line that Dickins later said "drove me crazy", but recognised its potential if it was worked on. Its pizzicato introduction, which has been compared to Andy Williams' 1963 single "Can't Get Used to Losing You", was the genesis of Roma's inspiration for the song's lyrics after she had heard the introduction as she looked out of the studio window and saw her children skipping. Dickins and Cullum are referenced in the lyrics in the lines: "We can steer, we can near with Rob Dickins at the wheel. We can sigh, say goodbye, Ross and his dependencies", the latter being a reference to the region of Antarctica known as Ross Dependency. Dickins only found out about it after the album had been pressed, which embarrassed him at first and initially wanted it changed, but soon warmed to it after the single went to number one. "All these years later", he said, "if I hear that line ... I can't help smiling."