For those not familiar with sea turtles, it might come as a surprise that there are several different types of large marine animals. Sea turtles, known for their lack of speed and hard, protective shells, have a wide range in sizes depending on which variety of sea turtles they are. Sea turtles are also some of the largest growing turtles compared to those that live along rivers and lakes. But how big can the various types of sea turtles actually grow?

The smallest type can grow up to just two feet in length and weigh only approximately 100 pounds, while the biggest sea turtles have clocked in at eight feet long. Here is a list of some of the largest sea turtles in the world.

Kemp’s Ridley

Size: Out of all sea turtles, the Kemp’s ridley is the smallest, and only grows to be about two feet long, weighing 70 to 100 pounds
Where are they found: Kemp’s ridley sea turtles are primarily found in the Gulf of Mexico but are less frequently found throughout the Atlantic Ocean, as far north as Nova Scotia

The Kemp's ridley turtle nests in the daylight
The Kemp’s ridley turtle nests in the daylight

The world’s smallest sea turtle, and the most endangered, the Kemp’s ridley (Lepidochelys kempii), is named for Richard M. Kemp, a fisherman from Florida who first submitted the species for identification over a century ago. It makes sense that the turtle species was first identified in Florida because the species is mostly found along the Gulf of Mexico.

The main threats to Kemp’s ridley turtle are egg poaching, climate change, and being caught by fishermen. 

Kemp’s ridley turtles are known for the darker shade on their sides, and adults have a grayish-green color on the top of their shells.

Olive Ridley

Size: Olive ridley turtles are typically between two and two-and-a-half feet long, weighing up to 100 pounds
Where are they found: Olive ridley sea turtles have been spotted in the Atlantic, Pacific, and Indian Oceans, primarily in the tropical regions

The olive ridley sea turtle is one of the most abundant turtles in the world
The olive ridley sea turtle is one of the most abundant turtles in the world

Credit: Brad Flickinger

Although many sea turtles come up on shore from time to time, the olive ridley turtle (Lepidochelys olivacea) is primarily an open ocean turtle, with some of the species being spotted more than 2 thousand miles from the shore. As the turtles spend most of their time in the water, they’re primarily found in the Atlantic, Pacific, and Indian oceans. Like all other species of sea turtles, the olive ridley, one of the world’s smaller sea turtles, is endangered, primarily due to fishing and the harvesting of turtles and their eggs.

Named for the green color of its shell, the olive ridley turtle is also distinctive because it has a heart-shaped shell. The animal’s size differs between populations, but the largest population of olive ridley turtles is in western Africa.


Size: Hawksbill turtles can grow to be between two and three-and-a-half feet long and typically weigh between 100 and 150 pounds
Where are they found: While Hawksbill turtles have been found in the Caribbean Sea and the Indian Ocean, the turtles primarily live near Australia and the Solomon Islands

Hawksbill turtles avoid deep water and prefer to live along coastlines
Hawksbill turtles avoid deep water and prefer to live along coastlines

The fourth-largest sea turtle in the world can be found in the Atlantic, Pacific, and Indian Oceans, as well as many of the world’s seas. While Hawksbills (Eretmochelys imbricata) are a few hundred pounds off of being the world’s biggest sea turtle, when they reach full adulthood, the turtles can weigh up to 150 pounds. The turtles are omnivorous, which means that they eat both plants and animals to bulk up to their largest size, including coral, algae, and sea sponges.

Hawksbill turtles are among some of the most unique sea turtles in appearance because they are irregularly spotted in a variety of colors, from red to black shades. The turtles are named for their lower jaw, which is shaped like the letter V, giving the sea turtles a hawk-like appearance.


Size: The flatback sea turtle can grow to be up to three feet long and weighs, on average, 200 pounds
Where are they found: Flatback turtles are mostly found in the waters near Australia and Papua New Guinea

The only place that flatback turtles breed and nest is Australia
The only place that flatback turtles breed, and nest, is in Australia

Although the flatback (Natator depressa) can weigh up to a fairly large 200 pounds, the big sea turtle is only the fourth largest sea turtle species out of seven. The flatback turtle is named for its shell, which appears to be much flatter than many other species of sea turtles.

While flatback turtles face common threats, like climate change and the harvesting of eggs and the turtles themselves, they’re also prey for animals like saltwater crocodiles, which have been known to attack nesting female flatback turtles.


Size: The largest loggerhead sea turtles can grow to be three-and-a-half feet long, but they can also be as small as two-and-a-half feet. Typically, the turtle species weigh between 200 and 350 pounds
Where are they found: Loggerhead turtles are widespread, being found in the Atlantic Pacific and Indian Oceans

The loggerhead is named for its large head
The loggerhead is named for its large head

Loggerhead sea turtles have been found in the Atlantic, Pacific, and Indian Oceans, as well as in the Mediterranean Sea. Despite how widespread the turtle species is throughout the world, they’re still endangered, with most populations having less than 10 thousand female loggerhead turtles nesting each year. The sea turtles’ population has decreased due to being bycatch for fishermen, climate change, and the harvesting of both the turtles and their eggs.

Loggerhead turtles (Caretta caretta) have large heads and are reddish-brown in color on the top of their shells, while they remain a light yellow color on the bottom of their shell.


Size: Green turtles are typically between three and four feet long but can grow up to four-and-a-half feet long. They typically weigh between 300 and 350 pounds
Where are they found: Green sea turtles are found worldwide, in subtropical and temperate regions of the Atlantic, Pacific, and Indian Oceans

Green turtles can not retract into their own shells
Green turtles can not retract into their own shells

Despite the name green turtle, not all green turtles (Chelonia mydas) have olive-hued shells. Some green turtles, which are the second-biggest sea turtle in the world, appear to have dark brown or gray colored shells, while others are green, as the species name suggests.

While green turtles are endangered, they do have 11 distinct populations throughout the world. Their population on Costa Rica’s Caribbean coast has approximately 30 thousand female turtles that nest each year, and the population near the Great Barrier Reef in Australia has up to 60 thousand female green turtles nesting per year.


Size: The largest living sea turtle, the leatherback can grow to be between five and six feet long and weigh between 750 and 1,000 pounds
Where are they found: The leatherback turtle is found worldwide, but primarily in the waters near Trinidad and Tobago and Gabon

Leatherback turtles have had the same form for 110 million years
Leatherback turtles have had the same form for 110 million years

There are no living sea turtles larger than the leatherback turtle (Dermochelys coriacea), which can weigh up to 1,000 pounds. The massive turtles don’t even have a hard shell to help add to the weight, as they’re the only species of sea turtle that doesn’t have scales and also does not have a hard shell surrounding it. 

While the species numbers are declining, large leatherback turtles are found almost everywhere throughout the world except for the Arctic and Antarctic Oceans. Like many other turtles, the leatherback turtle’s greatest threats include being bycatch in fishing nets, the harvesting of the turtles and their eggs, and climate change.


What was the biggest sea turtle in history?

Currently, the largest living sea turtle is the leatherback turtle, which can grow to weigh up to 1,000 pounds and is typically between five and six feet long. But that’s not the largest sea turtle in history — that would be the Archelon. The ancient sea turtle, which is extinct, lived during the Late Cretaceous era and could grow up to 15 feet long. Archelons could weigh up to 7,000 pounds, making it the largest sea turtle ever to exist. 

What can a leatherback turtle be compared to in size?

Leatherbacks, the largest living sea turtles, can grow to be pretty big, oftentimes growing to six feet long and weighing between 750 and 1,000 pounds. It may be hard to visualize a turtle that large, especially as they spend most of their time in the sea, but the animal can be compared to the size of a golf cart.

How many species of sea turtles are there, and are they endangered?

Currently, there are only seven different types of sea turtles, including the leatherback, Kemp’s ridley, Olive ridley, hawksbill, green, loggerhead, and flatback. Each of these turtle species is considered endangered or threatened. The Kemp’s ridley species, which primarily lives in habitats near the Gulf of Mexico, is the most endangered species of sea turtle.

How long can sea turtles live?

Sadly, few sea turtles survive into adulthood. Baby sea turtles face a lot of threats once they’re hatched, including disorientation while trying to make it into the ocean as well as predators like snakes and birds. But for those that do make it to adulthood, sea turtles live, on average, between 50 and 100 years. In addition to their lengthy lifespans, sea turtles are also among the oldest creatures on the earth — they’ve been around for more than 100 million years. 

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