Waterworld is a 1995 American post-apocalyptic science fiction action film directed by Kevin Reynolds and co-written by Peter Rader and David Twohy. It was based on Rader's original 1986 screenplay and stars Kevin Costner, who also produced it with Charles Gordon and John Davis. It was distributed by Universal Pictures. Wikipedia
The whole earth is mostly water - three - quarters ocean... And using water-streams and rivers and oceans - anybody could put a message in a bottle and send it all the way around the world. That's think we're solid, but we're not,. You can tell sometimes form your blood and tears and stuff that what you're like inside isn't what you're like outside, but usually you'd never know. Also, the whole earth is mostly water - three-quarters ocean. The continuants are just little stopping places. And using water - streams and rivers and oceans - anybody could put a message in a bottles and send it all the way around the world. Well, it's a good idea, but it's a no-good idea because of the curve in the river. The bottle couldn't get around it. Your battle would have a good chance from there. It'll give he wind and the water something special to carry. If you send something you care about, it might bring you luck.