9. Waterworld (1995)
Once the most expensive movie of all-time, and one of the biggest flops, audiences and critics have seemingly warmed-up to Waterworld over the years. The film depicts a planet where the ice caps have melted, creating a world ... of water ... where people live on floating atoll villages and do battle with marauding jetskiers (led by an eye-patch-wearing Dennis Hopper). Kevin Coster plays The Mariner, a semi-evolved good guy with webbed feet and gills who can breathe underwater and kick large amounts of ass. He also drinks his own urine. Seemingly ridiculous, Martin says the mutation angle holds water. "Mutations occur within a hundred years. Webbed feet and gills — these are things that easily adapted. You'd think there'd be more of them in the movie. Whenever any catastrophe hits the planet, historically, whatever animal and plant life survives, adapts. Everything has to adapt to survive, and so I think you’d see a lot more of that." Another element that rings true is the infamous urine purifying machine that Costner makes use of in the opening shot. "That's absolutely accurate. I have solar stills that I've built that use the sun to separate the ammonia nitrates out of urine and make water out of it. Your body is 80 percent water, and your urine is 99.9 percent water, and the rest is just minerals that you need anyway. Unless you have some disease or virus, your urine is very healthy."