Giant Sea Snakes: Discover the Largest Sea Snakes in the World

Written by Taiwo Victor
Updated: June 3, 2022
Image Credit Ken Griffiths/Shutterstock.com
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Think You Know Snakes?

Key Points

  • Sea snakes are mainly found in aquatic environments of coastal regions of the Indian Ocean and the Western Pacific Ocean.
  • The venom of a sea snake is some of the most potent out of all snakes.
  • Some of the largest sea snakes include the yellow sea snake, beaked sea snake, and the yellow-bellied sea snake.

Sea snakes are spectacular and mysterious sea creatures often very hard to find. They are restricted to coastal areas of the Indian Ocean and Western Pacific Ocean. Sea snakes have laterally compressed bodies and are often mistaken for eels. However, sea snakes are actually highly venomous snakes found in aquatic environments for most or all of their lives. Sea kraits are sea snakes that have flattened, paddle-like tails to help them maneuver in water easily.

Despite their marine adaptations, most sea snakes prefer to inhabit shallow waters near land, around islands, and sheltered waters. Closely related to the Australian venomous terrestrial snakes in the family Elapidae, Sea snakes are classified into two broad subfamilies. True sea snakes (subfamily Hydrophiinae) and the more primitive sea kraits (subfamily Laticudinae).

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The majority of adult sea snake species grow to be between 4 feet and 5 feet in length. The largest sea snake, Hydrophis spiralis, reaches a maximum length of 10 ft (3m) – one of the largest snake species in the world! Sea snakes have the most potent venom of all snakes in the world. Though the majority of sea snake species have gentle dispositions, some aggressive sea snake species are more irritable, and capable of killing an adult human in less than 30 minutes. 

Throughout the world, there are 17 genera comprising 69 species of sea snakes. Some species are notably larger than other species. In this article, we’ll explore seven of the largest sea snakes in the world. So read on to discover what we call the ‘giant sea snakes’!

Yellow Sea Snake

Hydrophis spiralis, the yellow Sea snake is the longest species of sea snake in the world, growing up to 3.0 meters long (up to 10 feet!) It is commonly seen in the northern Indian Ocean, as well as around Southeast Asia and near New Caledonia in the southwest Pacific Ocean. As its name implies, the yellow sea snake’s color is yellowish or yellowish-green above but the dorsal scales are edged with black. In the young Hydrophis spiralis, the head is black with a yellow horseshoe-shaped marking, but the head is usually completely yellow in the adult. Compared to most sea snakes, the venom of the yellow sea snake is usually less toxic and less copious. It feeds primarily on eels and is found in muddy, sandy ocean bottoms.

Stokes’s Sea Snake

Stokes’s sea snake is one of the largest sea snakes in the world.

Day & Haghe, Lithographers to the Queen / This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author’s life plus 70 years or fewer.

Hydrophis stokesii, Stokes’s sea snake, is a large species of sea snake in the family Elapidae. Located in the tropical coastal areas in the Arabian Sea, the Taiwan Strait, and northern Australia, Stokes’s sea snake is one of the largest species of sea snake in the world. Reaching a total length of up to 5 feet, and some individuals even measuring up to 6 feet, this species is one of the heaviest and bulkiest sea snakes in the world. They often vary in color, ranging from cream to grey to brown to black, with broad black dorsal crossbands. With fangs long enough to pierce a wetsuit, this robust sea snake has the longest fangs of any marine snake.

Olive Sea Snake

Olive Sea Snake
Olive sea snakes can grow up to 6.4 feet long.

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Aipysurus laevis, an olive sea snake, has brownish and purple scales along the top of its body while its underside is white. It is a large venomous sea snake species measuring about 3.2 feet, with some individuals growing to be about 6.4 feet (2m). 

The olive sea snake usually hunts in coral reef areas, using its special photoreceptor organs to remain completely hidden in the dark, safe from predators. Apart from its remarkable size, the sea snake species is highly venomous and it hunts small crustaceans, fishes, and benthic invertebrates, including prawns and crabs. Found in the shallow waters of the Indian Ocean, Western Pacific Ocean, and parts of Northern Australia, it spends its entire life cycle in the ocean

Yellow-lipped Sea Krait

The yellow-lipped sea krait’s venom is very toxic.

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Found in the tropical waters near the Indian Ocean and Western Pacific, the yellow-lipped sea krait (Laticauda colubrina) is a species of highly venomous sea snake from the Elapidae family. The yellow-lipped sea krait has a characteristic yellow snout (hence its name) and distinct black stripes with a paddle-shaped tail for swimming. On average, the body length of the yellow-lipped sea krait totals about 3 feet to 6 feet at maturity, one of the longest for a sea snake species. Females are significantly larger than males, with an average total length of 1.42 m (4 ft 8 in). Although they spend much of their time in the water, they can also return to land to digest, rest, and reproduce. They often encounter humans on land but they’re not aggressive, only attacking when provoked. The venom of Laticauda colubrina is highly toxic, and it uses to prey on eels and small fishes.  

Zweifel’s Beaked Sea Snake

The Zweifel’s beaked sea snake (Enhydrina zweifeli), also known as Sepik beaked sea snake, is an uncommon species of sea snake. It has a gray to brown body discoloration, a rounded snout, a notch at the jaws, and light-colored transverse bands that taper along the body. It can grow up to nearly 5 feet in total length, making it one of the largest sea snakes in the world. Commonly found in the temperate waters of Papua New Guinea and the Australian Coast, the Zweifel’s beaked sea snake feeds on smaller fish but occasionally preys on large fish such as catfish. They’re highly venomous and aggressive, reportedly known to bite under slight provocation.

Beaked Sea Snake 

Beaked sea snake (Enhydrina schistosa)
The beaked sea snake is the most venomous snake in the world.

iStock.com/Ekaterina Borisova

Enhydrina schistosa, the beaked sea snake (otherwise known as hook-nosed sea snake) is classified as one of the world’s deadliest sea snakes and the most venomous snake in the world. The snake is usually uniformly dark grey above; the sides and lower parts are whitish. An adult beaked sea snake grows up to an average length of 4 feet, while some larger specimens may be as large as 5.1 feet. They are highly venomous and notably aggressive, responsible for more than 50% of all bites caused by sea snakes and up to 90% of deaths from sea snake bites each year. This deadly snake is usually found in the Arabian Sea, Persian Gulf, and parts of Southeast Asia (especially on the coast and coastal islands of India). The beaked sea snake can dive into deeper waters up to 100 m and stay underwater for five hours to hunt for prey. Their primary source of food is fish.

Dubois’s Sea Snake

Most Venomous Snakes in the World - Dubois’s Reef Sea Snake
The Dubois’ sea snake’s venom is one of the most potent in the world.

Also a highly venomous species of sea snakes, Aipysurus duboisii is known as Dubois’ sea snake or reef shallows sea snake. Its venom is one of the most potent in the world, making it one of the leading most venomous snakes in the world – having the capacity to harm and kill humans with a single bite in under an hour. They are endemic to the coastal waters of Southeast Asia and Australia. Adults grow up to about 2.6 ft to 4.8 ft in body length and they are easily identified by their smooth dorsal scales, long fin-like tail, wide head, and series of dark brown crossbands on the skin. Living in depths of up to 262 feet (80 meters), Dubois’ sea snakes feed on moray eels and numerous fish species that live on the seafloor.

Yellow-bellied sea snake

Yellow-bellied Sea Snake
One of the most widely distributed snake in the world is the yellow-bellied sea snake.

Ken Griffiths/Shutterstock.com

The yellow-bellied sea snake, Hydrophis platurus, is one of the most widely distributed snake in the world. Unlike other sea snakes, it is completely pelagic, found in all tropical ocean waters around the world except for the Atlantic Ocean. Hydrophis platurus is the most commonly seen sea snake species in the world. Measuring between 2.2 ft to 3 feet, they are large sea snakes from the subfamily Hydrophinae. The yellow-bellied sea snake has a distinctive color pattern; a yellow underbelly and dark brown scales (hence the name, yellow-bellied), making it easily distinguished from other sea snake species. This incredibly venomous sea snake has a unique ability to swim backward and they hunt by floating on the surface of the water to attract pelagic fish.

Up Next…

Now that you have an idea of the largest sea snakes out there, take a look at these articles about sea snakes and other snakes that can swim! You won’t be disappointed.

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