I found that salt has no smell as its vapour pressure is too low. (Secretly, I slightly doubt that it has no smell, but the logic of that physical quantity can't be denied.) I foolishly ventured that you can smell the sea.
Of course we were almost as far from the sea as it is possible to get in England on this canal - and my question was immediately overturned, in stereo, with "that's the smell of di-methyl sulphide". So it isn't salt. It isn't ozone or 'fresh air' but it is a slightly toxic gas that gives the sea its nice smell
Apparently DMS is produced by bacteria and plankton in the sea. It gives the sea that characteristic smell and it plays an important role in the formation of clouds over the sea too.
Having googled the topic when I got home I found this interesting article, written by Sanjida O'Connell in 2009. It confirms what I had been told.