The classic silk square is definitely the Hermes scarf. And with every purchase, Hermes give you the knotting cards that gives you options on how to tie the scarf.
(via Maitai's Picture Book)
You can download all the 21 knotting cards HERE. And if this was not enough there are other options too, see this little video tutorial HERE. Why not an other tutorial HERE.
You can't stomack the pricetag of an original Hermes scarf (neither do I) any square scarf big enough will do. I've got two, one I got at Forever21 for 7$ and an other one for 20$ at American Apparel.
So here you go. wether you want to hide a case of bad beach hair, protect yourself from the sun or need a beach cover up, the suqare scarf is your beachy best friend !