Swimming in the Ocean: Is It Safe or Dangerous? (Solved!)

Seemingly everyone takes pleasure in a nice trip to the beach and going for a dip in the ocean water. However, although it’s a pleasurable pastime for many people, some of us wonder what potential dangers lie with swimming in the ocean.

It is generally safe to swim in the ocean, but there are a few health risks to be wary of:

  • Ocean currents can increase the likelihood of drowning.
  • Ocean water contaminants can cause infection.
  • Volatile water temperatures can promote hypothermia or hyperthermia.
  • Marine life can injure swimmers if they feel threatened.
  • Sudden weather changes can present unforeseen obstacles.
  • It’s very difficult to gauge water depth.
  • Low underwater visibility can disorient swimmers.

These dangers can pose a severe risk to swimmers that are not as knowledgeable of ocean water swimming as they should be. For this reason, we will delve into all of these potential hazards so that you can set yourself up for a positive ocean water experience.

Risk #1: Ocean Currents Can Increase Likelihood of Drowning

One of the foremost dangers of swimming in the ocean is the possibility of facing hazardous ocean currents. There are largely considered to be three ocean currents that could do potential harm to swimmers:

  1. rip currents
  2. rip tides
  3. undertows

Each of these ocean currents listed above presents its own particular set of problems to swimmers. Consequently, if a swimmer does have an unfortunate encounter with one of these currents, they must tailor their safety approach to whatever current is troubling them.

The first step to dealing with these currents, however, is knowing what they are and how to identify them. So, to begin, let’s explore rip currents in greater detail.

The Dangers Associated with Rip Currents

Definition of Rip Current: narrow water channels that move rapidly away from shore, developing from wave interactions with the unique structure of the ocean floor

Seeing the waves break and wash up onto the beach is an alluring sight to beach-goers. Unfortunately, although these waves are an incredible sight to see, they’re also what feed rip currents, which are far and away the biggest safety risk for swimmers.

In fact, more than 80% of lifeguard rescues at surf beaches have to do with rip currents (source). That’s obviously well over the majority of lifeguard rescues. So if you plan on taking a trip to the ocean anytime soon, it will be in your best interest to learn as much as you can about this swimming hazard.

The danger of rip currents is that they have the capacity to pull swimmers away from shore. It’s doubtful that a swimmer will get back to shore again by swimming directly against the current. This is because rip currents typically move at speeds of 1 to 2 ft/sec, but they have the capability of reaching speeds up to 8 ft/sec (source).

For those of you that don’t know, a speed of 8 ft/sec is faster than any documented Olympic swimming time. Thus, swimmers are essentially left up to the mercy of the ocean under these circumstances.

In severe cases, a rip current may even result in death. In a recent study, it was found that there are over 100 fatal drownings per year due to rip currents in the United States alone (source).

If you do stumble into a rip current and start getting sucked out to sea, do the following:

  • Maintain a Calm State of Mind – Rip currents will not pull you underwater, so there’s no need to overly stress about keeping your head above water.
  • Abstain from Swimming Against the Current – Fighting against the current is often a fruitless endeavor. The only thing it does is tire you out and increase your risk of drowning due to excess fatigue.
  • Swim Parallel to Shore – As aforementioned, rip currents are relatively narrow channels. By swimming parallel to shore, you may escape the clutches of the rip current and stop yourself from being washed out any further.
  • Signal for Help – If you lack the energy to swim parallel to shore, shout loudly to any people nearby and wave your hands around to draw their attention.

Of course, it’s best to avoid rip currents entirely by not swimming into one in the first place. To identify a rip current, watch the following clip for visible cues that give away its location in the water.

The Dangers Associated with Rip Tides

Definition of Rip Tide: fast moving water that’s directed away from shore, arising from tides that pull water through a beach inlet

Although rip tides and rip currents seem similar in nature, they’re inherently different. Rip tides originate from tidal water movement, which makes them more predictable. Rip currents, on the other hand, originate from wave interactions, which makes them more unpredictable.

Inlets are not designated swimming locations since the chances of being swept away are simply too high.

For this reason, rip tides are not nearly as much of a prevalent issue for swimmers compared to rip currents, but this does not mean that they should be treated like so. On the contrary, rip tides do have the capacity to pull a swimmer away from shore forcibly, exactly like a rip current can.

Since inlets are typically high-traffic boat areas, you should signal to any nearby boaters or fishermen if you get trapped in a rip tide. They will be your best hope for safety.

The Dangers Associated with Undertows

Definition of Undertow: an under-current that’s directed offshore, developing from water that has flown back downhill after a wave has toted it up the beach incline

It’s a natural part of every beach for waves to break onto the shore. As waves crash onto the beach and the water recedes into the next wave, you may feel a noticeable pull as the water trickles back downward. This is what is known as an undertow.

Undertows are the least dangerous of the three ocean currents listed. Most people will be able to overcome this slight underwater pull. Since there’s no threat of being sucked offshore, all a swimmer has to do is time their walk back to shore to coincide with a break in the waves.

The only swimming demographic where undertows pose a real health risk is for younger, smaller swimmers. Their underdeveloped bodies may not be equipped to overcome the pull of the water as it resets for the next wave.

Consequently, younger swimmers may have difficulty regaining their footing if an undertow causes them to fall. As a result, they may be continually tossed about by the waves.

For this reason, you should thoroughly supervise younger swimmers at all times to minimize any potential risk of drowning.

Risk #2: Ocean Water Contaminants Can Cause Infection

In addition to dangerous currents, there are various contaminants present in ocean water that can threaten the safety of swimmers if they’re not careful. These contaminants consist of both natural-born impurities and artificial pollutants.

Natural Contaminants

Since ocean water quality is not regulated like pool water, there are bound to be some microorganisms circulating that do not bode well with swimmers.

Disinfecting chemicals—like chlorine—typically take care of these impurities for us. With a body of water as large as the ocean, however, there’s no telling what sort of toxins are concealed within these watery depths.

The prevalence of natural borne ocean water contaminants is mainly due to animal waste and stormwater runoff. Unfortunately, these natural processes bring a plethora of germs into the water that can inflict damage if they come into contact with swimmers. Prevalent examples of germs that may be harmful to swimmers include the following (source).

Germ NameResulting Illness
Cryptosporidiumacute gastrointestinal illness
Legionellaacute respiratory illness
Pseudomonasskin infection, ear infection, acute respiratory illness

Another type of natural borne ocean contamination is a harmful algal bloom (HAB). Algal blooms are collections of microorganisms—namely cyanobacteria and algae—that sprout uncontrollably, contributing mass toxins to the surrounding ocean water. These toxins negatively impact aquatic life and environments and sporadically cause sickness in humans (source).

Algal blooms are uniquely characterized by distinctly colored ocean water, like green, red, or brown. It is for this reason that algal blooms have earned the nickname of “red tides.” So if you see exotically colored ocean water, stay away!

Artificial Contaminants

Alongside natural-born contaminants, there are also artificial pollutants circulating in ocean water that can cause illness in swimmers. Sadly, the ocean contaminants brought about by humans are just as threatening, if not more, than the natural-born contaminants mentioned above.

Common examples of artificial ocean contaminants include the following (source):

  • detergents
  • herbicides
  • fertilizers
  • industrial chemicals
  • oil
  • sewage

In addition to the contaminants listed above, there’s another major ocean water contaminant linked with humans that’s quite disturbing to think about: human waste.

According to the Centers for Disease Control and Prevention, there are approximately 0.14 grams of feces on the average person’s body at any point in time (source). This is an unsettling statistic, considering how many people venture into the ocean at a public beach.

This is why it’s considered common courtesy for beachgoers to shower before taking a dip in the ocean.

To learn more about the health benefits of pre-swim and post-swim showers, click over to Should You Shower Before or After Swimming? (Explained!).

Ingestion of contaminated water is the most common route of transmission for those that contract recreational water illnesses. Once these germs get into the body, they can wreak absolute havoc. The best way to fend off these problems is to avoid gulping down large quantities of ocean water while swimming.

The illness that afflicts ocean water swimmers most often is diarrhea. You should be wary of the fact that there’s a realistic possibility of dealing with these symptoms, even if you’ve taken all the necessary safety measures beforehand.

Risk #3: Volatile Water Temperatures Can Promote Hypothermia or Hyperthermia

Another potential danger of swimming in the ocean is the fluctuating temperature of the water. Unlike your local swimming pool, the water temperature of the ocean is subject to change. Its temperature can drop or rise on a whim, affecting a swimmer’s core body temperature severely.

As a quick reference, here’s how the medical community defines hypothermic, hyperthermic, and standard core body temperature (source):

Type of ConditionsCore Body Temperature
Normal Conditions98.6°F (37°C)
Hypothermic Conditions<95°F (35°C)
Hyperthermic Conditions>104°F (40°C)

Both conditions are serious in that they prevent the internal organs from performing their normal metabolic functions.

If a swimmer suffers prolonged exposure to frigid ocean waters, this can be enough of a stimulus to provoke hypothermia. There’s an equivalent amount of danger linked with sustained exposure to warmer ocean waters in that these conditions are sufficient to cause hyperthermia.

For further information on how hyperthermic conditions arise in swimmers and ways to prevent these symptoms, click over to Why Your Body Feels Hot After Swimming (Explained!).

To get a better idea of what ocean water temperature range is relatively safe to swim in, refer to the table below. But, again, these aren’t meant to be hard and fast rules. Rather, they’re intended to be simple guidelines to help you make a more informed decision on whether or not the ocean is fit for swimming.

Type of ConditionsOcean Water Temperature
Ideal Water Temperature Conditions77 – 82°F (or 25 – 28°C)
Hypothermic Water Temperature Conditions<70°F (or 21°C)
Hyperthermic Water Temperature Conditions>87.8°F (31°C)
(sources 6, 7, & 8)

Remember that if you’re planning on swimming vigorously, the water should be slightly cooler to help stabilize your core body temperature. This is why competitive swimming pools are purposefully regulated to be a couple of degrees cooler than recreational swimming pools.

Risk #4: Marine Life Can Injure Swimmers If They Feel Threatened

If you’ve ever ventured into the ocean before, you likely encountered multiple kinds of sea life during your experience. Although most types of marine life are relatively harmless to humans, there are a couple of aquatic species to watch out for.


Jellyfish may be appealing to the eye, but they can leave a nasty sting if you get reckless and explore a bit too closely.

Fortunately, it’s not in the nature of jellyfish to intentionally sting humans. They only do so when an unassuming swimmer brushes up against their tentacles. However, even dead jellyfish can be dangerous to humans since their tentacles may still have retained the capacity to sting.

The majority of jellyfish stings are not that severe, resulting in mild discomfort. They’re actually somewhat common for open water swimmers that take to the ocean. In fact, jellyfish sting more than 500,000 people every year in the Chesapeake Bay alone (source).

However, there are certain jellyfish that leave more serious stings than others. The types of jellyfish that you should really watch out for are the:

  • box jellyfish
  • lion’s mane jellyfish
  • portuguese man-of-war
  • sea nettle

If there have been recent reports of these jellyfish species in the area, it would be prudent to reschedule your dip in the ocean for some other time.

Sea Urchins

Jellyfish aren’t the only kind of marine life that could be troublesome to swimmers. Sea urchins can also be harmful due to their spiky apparatus.

Sea urchins usually reside in shallower waters, including places like:

  • coral reefs
  • exposed rock left by receding waves
  • tide pools

Unfortunately, due to their shallow-water residential tendencies, it’s common for swimmers to step on these small sea creatures by accident, sending immediate pinpricks of pain shooting up through their feet.

Not only do sea urchins puncture the skin with their spikes, but they also release venomous toxins in the body. In addition, since sea urchin spikes are fragile enough to fracture under enough physical stress, these spikes tend to get stuck in a person’s body after contact (source).

It’s important to remove these spines as quickly as possible to ward off infection and stifle the spread of toxins throughout the body.

Needless to say, stepping on one of these spikes on your way out to the ocean will put a damper on your swimming plans. So tread carefully if the ocean floor is rocky beneath your feet.


When people think of danger in the ocean, one of the first things that come to mind is shark attacks. And honestly… who could fault them?

These elusive sea creatures are made to draw attention with their razor-sharp teeth and gargantuan appearance. The portrayal of sharks in various works of cinema, literature, and other forms of entertainment also don’t do anything to help quell the public’s fear of this notorious sea creature.

Although there have been shark attacks in the past, they’re infrequent. In fact, recent statistical calculations have shown the likelihood of being fatally wounded by a shark to be shockingly low.

Believe it or not, the odds of a fatal injury due to a shark attack are approximately 1 in 3.7 million. To put that into perspective, you’re more likely to die from a champagne cork than a shark attack (source).

So although sharks may seem scary, I would be more worried about accidentally running into a jellyfish or sea urchin rather than a shark.

Risk #5: Sudden Weather Changes Can Present Unforeseen Obstacles

The next major health risk on this list is the danger that comes with turbulent weather.

While you may enjoy a pleasant outdoor escape, the weather can change very quickly from when you leave the shore and the time you return. If the weather changes for the worse, you may unintentionally end up in the thick of an oncoming storm without even realizing it.

When you see a storm looming on the horizon, it’s best to get out of the water as quickly as possible. As the rain and wind pick up, the ocean waves may gradually get rougher, making it a struggle to get back to the safety of the shore. Moreover, a harsh downpour of rain can quickly cool your skin and increase the likelihood of hypothermia.

Check out Swimming in the Rain: Is It Safe or Dangerous? (Solved!) for further information on the potential risks of swimming in the midst of a rainstorm.

Aside from the rougher waves and hypothermic conditions, storms also bring with them the threat of lightning. Although rain doesn’t always precede lighting, it’s still one of the only reliable indicators swimmers have when determining whether or not lightning is in the area.

Swimming in the ocean during a thunderstorm is a recipe for disaster because lightning strikes large bodies of water frequently. In addition, water is a known conductor of electricity, so this can spell tragedy for anyone caught in the water when lightning strikes.

For all these reasons, you should get into the habit of checking the weather forecast before heading out to the ocean. This way, you won’t have to worry about any unexpected weather complications endangering your health and ruining your ocean outing.

Risk #6: Very Difficult to Gauge Water Depth

Yet another health risk that ocean swimmers must face is the inability to measure water depth definitively.

Every section of the pool has a sign at your local swimming pool that explicitly states how deep the water is in that particular area. Unfortunately, you get no such information when venturing out into the ocean.

To make matters worse, the water depth is in a perpetual state of flux due to the constant ebb and flow of the ocean tides. It can be a point of difficulty to differentiate between a rising tide and a falling tide, particularly for the untrained eye. Without this information, swimmers may be surprised at how quickly the water depth near shore can change over the course of a workout.

You can learn more about discerning tidal information by reading through How to Tell if the Tide is Coming In or Out (Helpful Guide).

Shallow stretches of the ocean can turn deep rather quickly once you swim a fair distance away from shore. This can be unnerving for some beachgoers, particularly if they’re not the strongest deep water swimmers to begin with.

The ocean floor is not a monotonous, flat surface like that of a pool. A shallow, sandy section of water can quickly turn into a steep drop-off where the bottom of the ocean is hidden from view.

For this reason, you must always stay within beach parameters and watch your footing. Otherwise, you may risk venturing into overwhelmingly deep territory that may spark feelings of panic.

Risk #7: Low Underwater Visibility Can Disorient Swimmers

Lastly, the murkiness of ocean water can be problematic for swimmers, especially if they plan to spend most of their time underwater. If you can’t see where you’re going, there’s obviously going to be a higher degree of risk involved.

Swimmers may assume that they can circumvent this issue by keeping their heads above water, but even that doesn’t put you out of harm’s way.

The murkiness of the water may conceal unprecedented dangers that you may incidentally come into contact with because you can’t see below the water’s surface.

For instance, you could be walking directly into a patch of sea urchins and not even know it. There might be a steep drop-off within the next couple of feet of ocean floor hidden beneath the watery muck. These are both hypothetical scenarios, but that doesn’t detract from how realistic these dangers really are.

Ideally, you want to swim in clear, uncolored water. Since we don’t live in a perfect world, this sort of scenario may be somewhat hard to come by depending on where you choose to swim. At that point, you may have to weigh the costs versus the benefits.

Why These Risks Shouldn’t Stop You from Ocean Water Swimming

Despite all the health risks listed above, you shouldn’t abstain from swimming in the ocean if it’s truly what you want to do.

Humans have been swimming in oceans for thousands of years despite these dangers without the knowledge you currently have. Plus, recreational beaches help mitigate any potential health hazards by using special safety precautions, which we’ll discuss next.

Lifeguards are Always On Duty

For one, lifeguards are posted up and down the beach’s shoreline, paying special attention to any swimmers in the ocean that look like they’re in danger.

Lifeguards are taught to rescue swimmers in peril and prevent such scenarios from happening in the first place. This is the underlying reason why lifeguards patrol so often and call out to swimmers whenever they see anything amiss.

This system is extremely effective at ensuring the safety of open water swimmers. According to the United States Lifesaving Association, swimmers at beaches patrolled by USLA sanctioned lifeguards have a 1 in 18 million chance of fatally drowning (source).

That’s even less of a chance than a shark attack. So, you have a higher likelihood of dying from a champagne cork than drowning under the care of USLA lifeguards. That’s pretty reassuring!

Marker Buoys Prevent Swimmers from Venturing Out Too Far

Plus, recreational beaches have marker buoys in place to keep swimmers at bay.

These marker buoys aren’t just there for show. The closer that a swimmer remains to shore, the safer they will be. These marker buoys help keep swimmers in check should they lose track of where they are relative to the beach.

These marker buoys also offer the supervising lifeguards a better indication of whether or not a swimmer has traveled too far away. Again, this allows lifeguards to stop a potential catastrophe from occurring before it even has a chance to manifest itself.

Lastly, these marker buoys also stop swimmers from wandering off into areas that are unfit for swimmers. They keep beachgoers in a safe, confined zone that’s unlikely to cause unexpected illness or injury.

Final Thoughts

After reading through this list of health risks, you may be under the impression that the ocean is a big, scary place. The ocean does have its hazards, but you now know how to bypass such risks effectively.

The combination of the knowledge you’ve gathered from this article and lifeguard supervision should be more than sufficient to leave you with an enjoyable swimming session in the ocean.

All content written by HydroPursuit is for informational purposes only. The material found on this site is not intended to replace professional medical advice, treatment, or diagnosis. Consult with an accredited health care provider prior to initiating a new health care regimen.

Sources: 1 2 3 4 5 6 7 8 9 10 11 12

Austin Carmody

I am the owner of HydroPursuit. I enjoy kicking back and getting out on the water as much as I can in my free time.

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