Hehehe. I made this discovery when I went swimming on a cruise. Since they fill their pool with seawater every day, it is, of course, saltwater. I dove in with a tremendous sinus headache, hoping that just the warm water would alleviate some of the pain. When I finished swimming 30 minutes later, my sinuses were clear as a bell. I didn't become clogged up again for the rest of the trip. God that felt good.