Sea snakes swim underwater to depths of up to 80 – 100 meters in depth. Land snakes that swim in lakes, rivers and bays can also dive underwater but only for short periods of time.
Generally, there’s definitely a chance that you will see snakes swimming underwater in both the ocean and in lakes and rivers.
If you are swimming in tropical oceans such as Northern Australia, you may find snakes swimming deep underwater. If you are swimming in a lake or stream, you’ll likely spot snakes swimming with their heads above water unless they are hunting for fish.
Do Snakes Swim Underwater?
Yes, snakes can swim underwater, although not all can.
It’s generally believed that snakes were all land creatures, but some evolved into the sea in search of food. With this evolution, which began 35 million years ago, sea snakes emerged.
We can divide water dewlling snakes into several categories:
|Type of Water Snake||Scientific Name||Where it Lives||Underwater Swimming?|
|Sea Snake||Hydrophiinae||Fully Aquatic||Yes – Up to 2 hours|
|Sea Krait||Hydrophiinae Laticauda||Semi-Aquatic||Yes – Up to 2 hours|
|Watersnake||Varies||Semi-Aquatic||Yes – Short Periods Only|
|Land Snakes (Other)||Varies||Land Dwellers||No|
Category 1: Sea Snakes
Sea snakes can swim underwater, spend their entire lives underwater, and get their nourishment there.
However, they need to come ot the surface for air.
Sea snakes can swim without stopping for a very long time compared to other snakes. In fact, most sea snakes can be underwater for an hour and a half to two hours without breathing and swim to depths of 80-100m.
(Interestingly, we think that this also means that they can’t sleep too long!)
Besides whales, sea snakes are the air-breathing creature who can spend the most time underwater.
Sea snakes prefer warm waters. This is because they remain cold blooded animals who rely on the warmth in the environment around them to maintain their internal body tempreature.
They are distinctive for their beautiful vibrant colors (often striped) and the fact they are highly venomous. In fact, sea snakes are some of the most venomous snakes in the world.
Read More: Do Ponds Attract Snakes?
Category 2: Sea Krait
Sea krait do swim underwater, up to 80m deep, for long periods of time. However, they have to come to land to digest food and lay their eggs. Because they spend some time on land, we consider them ‘semi-aquatic’.
Nevertheless, sea krait are more comfortable in the ocean, and will spend most of their time at sea. They still have a paddle-shaped tail like their sea snake cousins that has evolved to make them excellent underwater swimmers.
While sea krait are venomous, they are shy and rarely bite. They’re distinctive by their black-and-white stripes, which are also the reason for their colloquial name the “stripey sweater”.
Sea Krait are also excellent climbers on limestone and deep sea hunters. They actually team up with yellowfin goatfish and bluefin trevally to hunt smaller fish in amongst coral.
Category 3: Watersnakes and Land Snakes
Nearly all land snakes have the ability to swim on the surface of water, while only a few inland semi-aquatic watersnakes swim and hunt underwater. Inland dwelling watersnakes that are known to be regular underwater swimmers include the common watersnake and cottonmouth.
Land snakes that are swimming across waterways to get to the other side will usually only swim on the surface with their head above water. Nearly all snakes can do this.
Even watersnakes like the cottonmouth who have the capacity to swim underwater will usually have their head above water because it’s more comfortable for them.
The two main watersnakes that you’ll find underwater in inland waterways (the cottonmouth and common watersnake) hunt fish underwater. The common watersnake, which spends most of its life hunting alongside streams and lakes, will also dive into the water if even remotely startled by the presence of humans or predators.
While people often mistake the common watersnake and cottonmouth, the cottonmouth is venonous and the common watersnake is non-venomous.
Can Snakes Bite Underwater?
Snakes theoretically have the ability to bite underwater. We know this because they bite their prey (such as fish) while swimming underwater, and inject venom underwater, too.
However, snakes do not consider humans to be prey and will nearly always try to flee human presence rather than bite, so swimmers and divers rarely get bitten. However, if you act aggressively toward the snake, touch it, or corner it, then it may bite.
Sea snakes are highly venomous, so if you get bitten, you need to seek help immediately. Despite their high toxicity, there are very rarely deaths from sea snake bites. There are 62 species to be called sea snakes, with various levels of toxicity, but nearly all are considered venomous.
Sea krait, which you’ll often find on beaches, are also venomous, but also notoriously shy. They’re not likely to bite unless provoked. A common time when people are bitten is when they grab the snake’s tail and drag it out of the ocean onto land.
Common watersnakes are non-venomous, but are inclined to bite and strike repetitively if threatened. People often try to kill common watersnakes because they mistake them for cottonmouths. You’re always better off just giving the snake a lot of space rather than approaching it and getting bitten!
Cottonmouth snakes, which are frequent swimmers, are venomous and do bite when provoked. Again, don’t approach or startle the snake, and you’ll usually be okay. It will not approach humans in the water because it is afraid of humans, and it will usually stay well away from you if you’re swimming nearby.
There are species of sea snakes and inland watersnakes that can swim underwater. So, it is possible to see a snake swimming between your legs in both oceanic and inland waterways.
They may also be able to bite you underwater. However, because snakes are shy animals that fear humans, they’re likely to leave a lot of space between themselves and swimmers. It is rare to be bitten by an underwater snake, or even to come close to them, as they’ll nearly always swim away.
If an underwater snake swims toward you, it’s likely wanting to get past you rather than attack. As I’ve explored elsewhere, snakes almost never charge at you unless they’re in a highly manic state. You may be between the snake and its home.