Corrected entry: At the end of the movie, when Costner and friends do find land, it turns out to be Mt. Everest. This establishes the sea level at that time. Using that and going back to the middle of the movie, we see Costner diving into the ruins of a city where skyscrapers are evident. The tallest skyscraper is approximately 1800 feet high, which would leave a difference of, say, 4 miles underwater. It would be pitch black at that depth and the water pressure would kill a human that far down, gills or no gills.
Corrected entry: Paper is seemingly a rare commodity in Waterworld, but all the bad guys run around smoking cigarettes all the time.
Correction: True, but the Mariner and the old Scientist are the only ones who show any interest in it. The average population probably doesn't care, making it not too valuble even though its rare. Also, the smoker leader is seen throwing cigarettes out of cartons. These are pre-deluge cigs, not hand rolled.
Corrected entry: If dirt is so hard to find, why are all of the characters so filthy?
Correction: It's rust, not dirt all over them. The big metal island and the Valdez are very rusty. Run your hand over extremely rusty metal and you will get an orange\brown stain. It looks like dirt from a little ways away.
Corrected entry: Can planes, boats and jet-skis run on plain crude oil? There's no real petrol ever mentioned.
Correction: Crude oil isn't particularly difficult to turn into gasoline. Especially if the Valdez originally had a chemical engineer on board and passed on his knowledge to the descendants.
Corrected entry: Since Earth is covered by a salty ocean, fresh water is treated as a rare, expensive commodity. This makes no sense, because the human body requires a certain amount of fresh water each day just to survive. If whole populations are sustaining themselves, this means that they have access to fresh drinking water reliably each day. Regardless of how people ration their fresh water, it won't be enough to sustain all those people for a year, much less through generations of people so that they would forget about the flooding of cities.
Correction: I guess you never heard of rain water or condensation? There are plenty of ways to collect fresh water, enough for every individual to have enough to sustain himself/herself at least. If an individual can collect fresh water for himself a community can do it much more efficient, collecting more fresh water than they actually need and therefor can trade with others. Eventually a community can even find ways to filter salt water. There were probably hard times where people were forced to drink their own urine, but still its not impossible for humans to survive a world of salt water over many generations.
Corrected entry: In the opening scene where Mariner is sailing his boat into the distance, land can quite clearly be seen on the horizon up ahead.
Correction: That's not land, it's the empty space of sky between the horizon and the clouds. You can see the same effect later in the movie more when the 3 are eating the sea monster on the boat.
Corrected entry: The Exxon Valdez is designed to carry crude oil. Crude has to be refined into higher octane products to be used in jet skis, automobiles, etc. The refining process is difficult and requires large amounts of power. It would be impossible to do on the tanker itself. And it is extremely unlikely that the smokers would have come across high octane products on another ship. They tend to be refined near to their consumers and not shipped around.
Correction: Stating that it would be impossible is supposition, it would be possible to have a small refinery on the tanker - producing just enough fuel to keep the smokers running. The main components in a refinery are a furnace to heat the crude and a distilling tank to separate the petroleum products.
Corrected entry: If there were enough ice on the planet that, when melted, would raise the ocean levels to the extent shown in the movie, then the saltwater would be diluted enough to be drinkable, negating the plot point about "hydro" being such a valuable commodity.
Corrected entry: It is a known scientific fact that a planet without land will create waves rising from 500 to a thousand feet. This is because there is no land that can break the waves' rise. This would make the surface uninhabitable by any man-made structure or vessel especially with Waterworld's current human technology. Waterworld barely has any waves.
Correction: It is not a known scientific fact. It is one scientific theory that is impossible to prove. Computer models can only begin to guess at the effects of no land above water. And in Waterworld there is at least one landmass which they find, and there are probably more as the melting ice-caps are not sufficient to cover the entire surface.
Corrected entry: It doesn't make sense that the Smokers have so many shells. In the Atoll Assault scene the four-barreled machine gun chassis is dumping out about 50 shells every 4 seconds.
Correction: We don't see the world being flooded and the smokers becoming what they are. Who's to say they didn't find an ammunition stash or battleships (which I'm sure would still be floating around) and raided them.
Corrected entry: The woman and the little girl escape with Kevin Costner off the metal island in a big hurry and can be seen taking no bags or clothes with them. Why then, in a later scene aboard Kevin Costner's boat, does the woman have a completely different dress on from the one she escaped in?
Correction: It is quite possible that there was a woman's dress aboard Kevin Costner's boat already and the woman just changed into it. Since the clothes they are wearing are a lot like rags, the individual bits and pieces can be rearranged easily so as to look like a different dress. It is also possible that the woman was wearing 2 (or more) sets of clothes simultaneously while escaping from the metal island and simply took one off.
Correction: She was stitching something together in the movie, while on the boat shortly after he chops thier hair off, it could have been the other dress.
Corrected entry: Why did Costner's character have to use that timer thing to gauge how long he is underwater? He has gills so he should be able to breathe underwater therefore he wouldn't have to limit his exploring time so much.
Correction: The timer was to trigger the winch to pull up all the loot.
Correction: My theory on this is so he can make sure his awesome boat isn't left unattended for too long but that's just my thoughts.
Correction: Considering how scarce fresh water is and how easy it is to desalinate seawater, there could be chemicals in the sea after the war. Maybe the he sets the timer because he knows that staying down much longer will make him sick.
Correction: Could be he was timing for the sleeping cycle of the large sea creatures roaming the oceans. He doesn't want to be caught so deep when those things show up.
Correction: We have no idea how long in the future this movie takes place, assuming earth should reach its maximum human holding capacity in about 2025, it is not out of the question that skyscrapers could exist at a higher altitude. Also, there would not be nearly enough water to cover the earth to that depth. This leaves the requirement that the mountains have to sink, entirely possible due to the pressures of the changing water levels, or tectonic disturbance.
Sol Parker