There is a series of four readings by Robert Macfarlane from his book "The Wild Places", the first of which is here:
Episode 1: island
or you can visit Toast:
http://www.toast.co.uk/content/TheWildPlacesAW07.htm?menu=media
where you will be able to listen without downloading, and where you will also find the other three.
It's like having someone read to you - perfect for when you can't sleep.
