Our oceans are among the oldest features of Earth and tend to play a vital role in the age-old mythologies of various cultures. Within these ancient and expansive bodies of water, civilizations tell tales of abominations that once ruled the seas, impossible gods, and monsters of yesteryear that helped compile this list of the ten scariest mythological sea monsters. Here are the top ten scariest mythological sea monsters.

The Kraken

A classical creature first detailed in 12th century Norway, the Kraken has morphed into a variety of different on-screen and literary monstrosities. In The Natural History of Norway, Bishop of Bergen, Erik Ludvigsen Pontoppidan, described the Kraken as the largest sea monster in the world with a width of up to 1.5 miles (2.4 km) and starfish-like protuberances. Though the gruesome picture of a ship-sinking sea monster was diminished slightly in the 18th century when French scientist Pierre Denys de Montfort linked it to a large kracken octopus, ultimately, it’s commonly agreed that the oversized Kraken was really just a giant squid terrorizing the Norwegian coast.

Umibozu

Technically a spirit from Japanese folklore, the Umibozu is still a mythological devil of the deep blue. The big-headed mischievous atrocity is said to capsize the ship of any brave soul that addresses the sea-dwelling creature. Other lore of the Umibozu paints it as a demonic entity, thought to be drowned priests that indiscriminately shipwreck those that cross its path. Often depicted as a serpentine with a cloudy body and a shaven, humanoid head, the Umibozu is said to appear on calm nights to wreak havoc on ships. If it doesn’t outright destroy a vessel, it demands a barrel from the crew, which it fills with water and dumps on the deck of the ship to sink it.

Tiamat

In Mesopotamian mythology, Tiamat is described as the physical representation of the sea, making her the ultimate sea monster. As the goddess of saltwater, Tiamat mated with Abzu, the god of freshwater, to reproduce and give life to the lesser gods. According to legend, Tiamat and Abzu intended to kill the lesser gods, but when intercepted by Ea and Marduk, the two were slaughtered. Marduk cut Tiamat in half and used her body to create the sky, the earth, and the clouds while her tears formed the Tigris and Euphrates. Originally depicted as a dragon or sea serpent, Tiamat’s popularized form as a multi-headed dragon spawned from Dungeons & Dragons in the 1970s.

Jormungandr

The beast of Norse mythology, Jormungandr, is also known as the Midgard Serpent or World Serpent and inhabits the ocean surrounding Midgard. A child of Loki and Angrboda, Jormungandr was dispelled into the ocean by Odin, and it was there that it grew massive enough to encircle the Earth. The serpent is of simple design, but its formidable size is impressive, making it a match even for its rival, the God of Thunder, Thor. Jormungandr is said to wrap around the world and grab hold of its tail. When it lets go, Ragnarok, or a massive battle akin to the “Viking apocalypse,” is prophesied to begin, resulting in the deaths of Odin, Thor, Loki, and other major Norse deities.

Qalupalik

This mythological creature from Inuit folklore may not be the largest monster on this list, but it is undoubtedly one of the most disturbing. Described as a humanoid with long hair, greenish skin, and long, slender fingernails, the Qalupalik is said to target disobedient children and take them away in their amauti, which is a pouch traditionally used by the Inuit to carry children.

Like a sea-dwelling Krampus, the Qalupalik takes children back to her lair underwater, where they remain forever. The haunting humming of this sea-witch was said to lure children away from their parents for an easy grab. The Qalupalik is a reminder that not all sea monsters are colossal creatures; sometimes, the smallest and seemingly innocuous beings can be just as terrifying.

Hydra

This is a creature from Greek mythology that may be familiar to many of us. The Hydra was a massive, multi-headed serpent-like creature with poisonous breath and blood. Every time a head was cut off, two more would grow in its place, making it a formidable foe.

The Hydra was eventually slain by the Greek hero Heracles, who used fire to cauterize each wound after severing a head. The Hydra’s blood was also poisonous, making it an even more dangerous creature to face. The Hydra has become a staple of popular culture and continues to inspire new stories and interpretations to this day.

Leviathan

This is a well-known sea monster from Jewish mythology. Described as a massive creature with impenetrable scales and fiery eyes, the Leviathan was said to be a fierce and dangerous beast. The creature was said to have been created on the fifth day of creation, along with other sea creatures, and was often depicted as a symbol of chaos and evil.

In some traditions, the Leviathan is said to have been slain by God and served as a feast for the righteous in the world to come. In others, the creature was said to be too powerful to be defeated and would remain a menace forever.

Charybdis

The Charybdis is a sea monster from Greek mythology. Described as a massive whirlpool, the Charybdis was said to create a deadly vortex that could swallow ships whole. According to legend, the Charybdis was once a beautiful nymph who was transformed into a monster by the god Zeus as punishment for her greed.

The Charybdis was said to be located opposite the monster Scylla, creating a treacherous passage for sailors to navigate. In popular culture, the Charybdis has appeared in numerous films, television shows, and video games, often portrayed as a massive, swirling vortex that threatens to consume anything in its path.

Iku-Turso

Iku-Turso is a mythical creature from Finnish mythology. It is often described as a giant sea monster or a demon of the underworld. The name “Iku-Turso” means “eternal Turso” or “eternal monster” in Finnish. In some legends, Iku-Turso is said to have been created by the god of the sky, Ukko, to guard the underworld. It is also sometimes associated with the god of the sea, Ahti, and is said to have power over the winds and the waves.

Iku-Turso is usually depicted as having multiple heads and a body covered in seaweed or other aquatic plants. It is often shown carrying a club or other weapon. Despite its fearsome appearance, Iku-Turso is not always seen as purely evil, and in some stories, it even helps heroes on their quests.

Cthulhu

Finally, at number one, we have the Cthulhu, a sea monster from the works of H.P. Lovecraft. Described as a massive creature with a squid-like head and wings, the Cthulhu is a cosmic horror that is said to exist beyond human comprehension.

The creature is worshipped by a cult of followers who seek to awaken it from its slumber and bring about the end of the world. The Cthulhu has become an iconic figure in horror literature and has inspired numerous adaptations in film, television, and other media.

The sea has long been a source of fascination and terror for humanity. From ancient mythologies to modern horror stories, sea monsters have captivated our imaginations and inspired countless tales of horror and wonder. The ten creatures on this list represent some of the most terrifying and awe-inspiring monsters from the depths of the ocean, each