Check this out! A very fascinating press release article from the Van Gogh Museum, which can be found at any of these webpages:
(1) http://www.vangoghmuseum.nl/1015-newsdb/nieuws?action=nieuws_view&id=263&cat_id=4
(2) http://www.codart.nl/exhibitions/details/751/
(3) http://www.absolutearts.com/artsnews/2004/06/18/32136.html
This article adds a different dimension to the significance to the Sea imagery in Van Gogh's paintings.