Do Hippos Swim or Float? The Full Guide

Hippopotamuses, popularly called Hippos, are semi-aquatic mammals. What this means is that these mammals, live in water bodies but not entirely. Hippos immerse half of their bodies in the water, thus, adopting an aquatic lifestyle. Lovers of nature and wildlife have repeatedly asked one question which is whether or not hippos can swim.

How fast can a hippo swim? Hippos are known to swim at a speed of 8 kilometers per hour underwater. Due to the weight of the hippopotamus which is at least 1500 kg, it is quite difficult for it to swim underwater.

Note, however, that the hippo does not live in just any body of water. They prefer and choose slow-moving rivers and lakes just like the ones found in the Sahara Desert of Africa. 

Now we shall have a look at various subjects that support the theory of Hippos and their semi-aquatic lifestyle.

Do Hippopotamuses Swim or Float?


The body weight and body structure of the hippo cannot be compared to any other aquatic mammal. Regardless, the hippo spends most of its lifespan in water bodies. Hippos cannot swim but they can move underwater by charging through the water bodies.

Research has shown that hippos can hold their breath long enough to allow them to immerse their bodies entirely and not just partly, in an aquatic environment.

Hippos hold their breath for up to 5 minutes while settling underwater. When they need to move underwater, they return to the surface of the water to take in the air. This is how hippos live underwater throughout their life.

Why Do Hippos Swim Instead of Living on The Ground?

‘Hippopotamus’ is a Greek word that means “river horse.” Although the hippo’s weight, body structure, and lifestyle cannot be compared to that of a horse, it is still referred to as a river horse because of its survival underwater.

Hippos have a unique skin type that demands wetness through a dry season. However, hippos do not sweat and since they cannot survive on the ground for too long seeing as their bodies begin to dehydrate and due to the absence of sweat glands, they are exposed to the likelihood of blood sweat.

Yes! Instead of sweating, the hippos’ body pours out sweat in the form of blood which forms a layer of mucus. This layer of mucus helps to moisten the body. These blood sweat layers also work in decreasing the hippo’s exposure to diseases and infections from unclean water bodies.

Studies have shown that a hippo spends an average of 16 hours per day underwater and only returns to dry land in search of food. Their diet consists mainly of grass.

How do Hippos Maintain Neutral Buoyancy Underwater to Swim?

Humans have always marvelled at the fact that hippos can swim and even spend more than 75% of their lifespan underwater. However, there is a scientific explanation for this. Hippos can gain neutral buoyancy underwater despite their round, heavy physique.

The Hippopotamus has a natural osteosclerotic disorder within its appendicular skeleton. This means that their bones harden abnormally and their bone density elevates. 

This disorder results in extra bone weight added to the body weight. Thus, using a combination of their bone weight and elevated bone density, hippos gain neutral buoyancy underwater which helps them to swim/walk underwater with little to no resistance.

If hippos do not have the osteosclerotic skeleton, they would experience difficulty in adapting to a semi-aquatic environment, because a lot of energy would be needed to stay underwater and light-weight bones can result in them drowning.

Can Hippos Sleep Underwater?


Hippos can sleep underwater and this is an impressive lifestyle adaptation as they are semi-aquatic mammals with a heavy physique. An adult hippopotamus can hold its breath for up to 30 minutes underwater.

Thus, when they sleep underwater, hippos usually have to return to the water surface after about 20-30 minutes to inhale the fresh air, then go into the water once again. What is most fascinating is that during this underwater respiratory process, the hippo does not wake up from sleep.

Can Hippos Swim in The Ocean?

The basic answer is no, as most hippos cannot swim in deep waters. As mentioned earlier, hippos do not swim but rather walk underwater. For this reason, if the water is deep, such as the ocean, hippos cannot go beyond a certain level.

A few subspecies of hippos, however, have evolved to swim in deep waters due to their low-density body structure.

Studies have shown that hippos can swim in the ocean only when the water level is stable. Certain wildlife researchers around the world have encountered situations where hippos were recorded swimming in oceans like the Atlantic.

Hippos have also been found in the sea and oceans of southern Africa. Undoubtedly, oceans are quite deep and this makes it difficult for hippopotamuses to swim through. However, some Hippopotamuses have been caught living in the blue waters of the bay.

Can Hippos Drown?

Hippos cannot drown as their heavy bone structure keeps their body afloat. The hippo’s ability to move in locomotion style also enables it to sleep underwater without drowning.

How Do Hippos See Underwater?

A hippopotamus can see underwater; this is weird but true. When hippos immense their heavy bodies underwater, a clear membrane covers the surface of their eyes and allows them to see beneath the water surface. These membranes come naturally and resemble ‘goggles.’

Thus, even though hippos need to close their nostrils to avoid drowning and close their ears to avoid water entering into their ears, they can still keep their eyes open, watching and observing the aquatic environment.

Do Hippos Eat Aquatic Plants in Water?

The hippopotamus feeds on small grasses and reeds that grow in the grasslands around water bodies. Hippos do not eat the aquatic plants underwater because they cannot eat with their nostrils and ears closed. They can only graze on grass that grows on land.

In bad climatic conditions, hippos eat aquatic plants. However, these aquatic plants make up just a portion of the hippo’s diet. This usually results in most hippos migrating to a different location.

Can Hippos Survive Without Water?

Hippos are considered semi-aquatic mammals; thus, water bodies are a significant part of their life. Hippos can only be found in an environment that has a dry-wet season as it allows them to have access to vegetation they can feed on and slow-moving water bodies to keep their bodies from overheating.

Final Thoughts

Hippos are considered as one of the fastest runners on land. An adult hippo can run at 30 kilometers per hour on land. In water, they move at 8 kilometers per hour.

See Also

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