Oh... the lyrics.
(I can't hardly understand 'em in spanish)
So you must be still laughing on my Dylan's 'Highlands' post.
Anyway, beside words IMO there is some kind of febrile lay down atmosphere, a monotonous thing were time goes by 'n by, and nothing changes.
I love this sort of songs when sailing oceanic with my buddy. We play that 17' song quite often. 'Isis' is another long good one.