What are ley lines in occult?

They were originally postulated in 1921 by the archaeologist, Alfred watkins who noticed that historical sites in Britain tended to follow predictable paths. He reasoned that these were laid out to create visible landmarks for people as they walked from place to place. So in that sense, Ley Lines are not part of the occult.

However, more recently, these supposed lines were adopted by New Age types to indicate natural energy centers whose connectivity brings greater harmony to people and the earth. So in that sense, yes, Ley lines are part of the occult.

Hope this helps.