I have a question about the seas and ocean we swim in. How does the Ocean get rid off all the natural pollutants (for example dead animal debris) and man-made pollutants (human waste, garbage, etc)? I know that there's salt in the water, which helps to kill bacteria, but does salt really do that much? And also, I heard that the Ocean is so big, that pollutants are naturally diluted through the waters, making it safe. Is this true?

Oh, and I don't mean those giant plastic garbage deposits out in the middle of the ocean, I'm talking about our beaches and seas.

I'm asking this because I never see any brownish murky water whenever I go swimming. Any feedback would be highly appreciated. Thanks!


1 Answer 1


You hit on the main reason why sea water is fairly clean, which is the fact that the sea is so vast. Salt water kills some micro-organisms, but by no means all. The sea is teeming with countless trillions of them, some dangerous but most not. The sea is full of hungry animals which feed on animal detritus. Some of these animals are small, like anemones and corals, and some are large, mostly species of fish and hagfish. Some dead vertebrates like whales sink down into the abyssal ocean depths, where they provide a feast for various deep sea creatures. This has been going on for many millions of years, and many a dinosaur has been eaten and dissolved away by creatures beneath the waves.

The many plants (sea grass and mangroves etc) and algae (seaweeds) also require nourishment, some of which comes from non-biological sources, and some from the excreta and decaying bodies of birds and other animals. Plastic is washed ashore and broken down into smaller and smaller fragments. Some beaches around the word are sufficiently polluted that they are classed as dangerous, and unfit to swim in, but may nevertheless seem to be clean. A few such beaches are in UK, so there must be some in America as well.

  • $\begingroup$ What stops the food chain cycle from staying in our Seas? $\endgroup$
    – user17688
    Sep 15, 2019 at 23:52
  • $\begingroup$ @FuzzySquid What makes you think it does stop? Please respond by editing your question. $\endgroup$
    – Spencer
    Sep 17, 2019 at 15:04
  • $\begingroup$ In Micheal's answer, he talked about how many plants and animals constantly eat each other, so what I meant to ask is how does it make our waters clean? If the food cycle is in our Seas, then wouldn't that pollute the water with debris and fish waste? $\endgroup$
    – user17688
    Sep 18, 2019 at 2:20

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