Looking for a sword and Sorcery book I read a while back
Trying here first before going to the less specific "find a book" reddits
I've been reading Sword and Sorcery books (among others) since the 60's, starting with Conan, Fafrd and the Grey Mouser, Elric, etc., so there's a lot of water under the bridge and a lot of books to try to remember.
There's one a can't remember and no longer have that I'd like to read again. I think I read it in the late 80's or sometime in the 90's
All I can remember is that at one point, the ship the MC is on is hiding in some marshlands for some reason among some tall reeds. They are continually attacked by invisible monsters until someone comes up with the idea of spreading flour on the deck so at least they can see the footprints as the monsters appear. At one point, small human footprints appear that belong to an invisible human girl.
Thanks is anyone knows what book this is