When I went to the stamp show a couple of weeks ago, I ended up buying one of those books that some collectors used to have with pages of stamp pictures that you added your own stamp to as your collection grew
and came away with about 1800 stamps all from before the 1970s and several from countries that no longer exist or have changed name (perhaps a few times) I haven't figured out what to do with them yet - the binder is massive and there are several empty pages.
so I searched through it for something water themed and found this example with this stamp from Guinea in West Africa celebrating the moon landing in 1969 - in English and French!
and in memory of the recent floods from Hurricane (Superstorm) Sandy and Typhoon Son-Tinh (Ofel),
this Flood rescue stamp issued in in the UK Sept 2009
see more water at Viridian's Postcard Blog