Water Hazards

Have you ever wondered what it means when you hear “natural” water? Isn’t all water natural?

Natural water refers to streams, rivers, lakes, and oceans that occur naturally or are man-made (example: lakes that are formed by rivers with dams). Another common name used for it is open water.

Whenever swimming in natural waters, always keep these tips in mind:

  • Find out where to swim on www.nps.gov
  • Always wear a life jacket
  • Designate a “Water Watcher” to supervise children, inexperienced swimmers, and those who cannot swim even in lifeguarded areas

Natural water is very different from swimming pools. Learn more about 5 common hazards in natural waters and find out how you can reduce the risk of drowning when recreating in, on, or around water.

Natural waters have currents which are moving water. Some currents are very easy to see. Think about waves in lakes and oceans or white water in rivers. Other currents are difficult to see or not visible at all. For example, rip currents in oceans or lakes or river currents that look calm on the surface but are moving fast underneath.

Currents are difficult to swim in, even for an experienced swimmer. They can tire you out and make it difficult to get back to shore. Currents can also move you downstream or further out into the ocean very quickly.

When recreating in a natural body of water:
  • Find out where to swim on nps.gov or ask a Ranger when you arrive at the park
  • Find out if there are any safety warnings related to currents and water levels
  • Always wear a life jacket
If you are caught in a current:
  • Don’t fight the current
  • Swim parallel to shore if caught in a rip current
  • Swim across a strong river current to reach shore
Learn more about swift water in rivers.

You and your friends spot a cool rock formation on the shore across the lake or river. Looks like a fun place to explore and its right there. You can easily swim over to check it out, right? WRONG!

Distance across water can be very deceptive. Not only is the distance greater than it looks, but you will also have to swim against strong currents and even waves before you get there. Swimmers, even experienced ones, quickly become tired and are unable to swim back to shore. The likelihood of drowning increases, especially if you are not wearing a life jacket to help keep you afloat. It can take time for rescuers to arrive.

When recreating in rivers and lakes:
  • Stay close to shore
  • Don’t swim to rocks or other formations in the middle of the water or to the opposite shore
  • Always wear a life jacket
It’s a hot summer day. You’ve been hiking and come across an inviting river, lake, or ocean in which to cool off. You jump in and…SHOCK! You begin to gasp and shiver instantly. The water is very cold!

Many of the natural bodies of water in national parks can be colder than 80°Fahrenheit (F), even in summertime. Some stay below 50°F even in July.You might be thinking “Isn’t 80°F very warm?”. When applied to air temperature yes, it is very warm. But your body does not experience water temperature the same way it experiences air temperature.

You can feel the effects of cold water starting at 77°F. Swimming in water colder than 70°F lowers your body temperature and can lead cold shock. Cold shock makes it difficult for you to breath and swim. Cold water can even lead to drowning if rescue does not happen quickly.

If you decide to recreate in cold water:
  • Check water temperatures before entering the water
  • Always wear a life jacket
  • Wear a wet suit or a dry suit, depending on your activity
  • Limit your time in the water
Learn more about cold water at the National Weather Service.

Natural bodies of water often don’t have a gradual change in water depth like you may find in swimming pools. Uneven bottoms, low tide shelves, ledges, or holes can suddenly increase water depth and leave you unable to touch the bottom. Water depths above chin level can be dangerous, especially for inexperienced or non-swimmers who are unable to keep their head above water or swim back to shore.

When recreating in a natural body of water:
  • Find out where to swim on nps.gov or ask a Ranger when you arrive at the park
  • Always wear a life jacket
  • Designate a “Water Watcher” to supervise children, inexperienced swimmers, and those who cannot swim even in lifeguarded areas
When it comes to natural waters, most of the time you can’t see below the surface of the water because the water isn’t clear. Fallen trees, plants such as grasses, or large rocks can often be found at the bottom. You can become entangled and trapped in these underwater hazards and unable to swim back to shore. Natural water can also have unexpected shallow areas caused by sandbars, trees, and rocks. Diving or jumping in the water in these areas can result in serious injuries.

When recreating in a natural body of water:


Additional information can be found on swimming in our article on Go for a Swim in a Park. Read on to learn more about water hazards in parks...

Last updated: April 25, 2022

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