I agree it is very hard to make head or tail of or "crack" its meaning. Even large, well-preserved stone circles, tombs and alignments are still bound in mystery and conjecture. Seahenge seems to me a piece of strange ephemera... original intent... like catching fog in a net...
Btw, my thoughts are (probably influenced by being a gardener) the central oak was a way of making offerings to the earth, it makes perfect sense really. (well to me) The upside down nature was so the roots "drew" offerings down into the earth. in it's natural life the roots were responsible for drawing up nutrients, turn it upside down and it could perform the same but in reverse. i've never heard another theory that makes any sense at all.
Anyone else care to offer their theory. ?
Chris Collyer's photo is iconic, a romantic image caught in the present time and not reflecting its original stance in the landscape, and there comes to mind the 19th century romantic tourist, scenery was all 'the moping owl in the ivy turreted tower' is pretty but the ivy is destroying the tower.....
http://www.themodernantiquarian.com/post/4264/sea_henge.html
Celtic imagery fits in very well with the tree with its trunk buried in the earth, to another 'upside down world' in which all things return to the ancestral but who knows.
The Lynn Museum did a good job with the installation of the posts, though sadly the great tree trunk is to the side and not in the centre of the half ring of posts. It is magnificient, as are the posts and I suspect more people will understand our prehistoric past by seeing them in this reconstruction than they would have on a beach where they were fast disappearing....
Btw, i'm sure i read somewhere they plan on burying it to preserve it, if that happens it'll be a huge smack in the face for archaeology, and excellent ammo for the anti excavation people.