Cruel Sea
General information
Series Walking with Dinosaurs
Episode no. 3
Featured animals Ophthalmosaurus
Broadcast information
Original airdate 30th April 1999

Time of Titans


Giant of the Skies

Cruel Sea is the third episode of Walking with Dinosaurs. It first aired on 30th April 1999, and was filmed in the Bahamas and New Caledonia.

The episode focuses on the Jurassic seas around present-day England, and features marine reptiles such as Ophthalmosaurus, Liopleurodon and Cryptoclidus, as well as Eustreptospondylus, a dinosaur.


In a flooded Jurassic England, a Eustreptospondylus is peering into the water when it is caught by a massive Liopleurodon.

A Cryptoclidus pulls itself from the land into the water, where it is more graceful. They prey on Ammonites and jellyfish. One passes a shoal of pregnant Ophthalmosaurus which are moving through the water, all looking for deep water to give birth in. The Cryptoclidus hunt using unique fin movements.

On land, the Cryptoclidus are basking in the sun. Above then is a flock of Rhamphorhynchus, combing the beach and ocean surface for fish.

In the deep, the Ophthalmosaurus are beginning to give birth live young, a slow process. One individual is approached from behind by an old male Liopleurodon. Her pups reach the surface for breath, and flee into the coral.

Another female is struggling to give birth near the surface - her splashing attracts some Hybodus sharks. After twenty minutes, she is still struggling, and the sharks are coming closer. The male Liopleurodon shows up, scaring the sharks away in the process, and bites the icthyosaur in half, her back half falling to the ocean floor as food for the sharks. The Liopleurodon is stated to be over one hundred years old.

The network of coral caves nearby is home to the hordes of baby Ophthalmosaurus. The babies have teeth, unlike the adults, and a young male tries to eat an Ammonite, to no effect.

With little food on land, an individual Eustreptospondylus swims across the shallow waters towards another island. He makes it to the other side, and shakes himself dry before going into the woods. He finds a dead turtle, but another Eustreptospondylus is already eating it. Despite the fact that only a decaying shell remains, the two dinosaurs fight over the food. Not wanting to risk injury, they simply roar at each other, and the male is scared off, back into the woods.

In these woods, a young Rhamphorhynchus - a fish eater - is trying to eat bark beetles in a tree, but fails.

Two weeks after their birth, the Ophthalmosaurus babies are growing well, but are still at risk of Hybodus attacks. One pup hides in a head of coral from the shark, but runs out of air. Still, he manages to escape the ambush set up by the shark, which does not need to go up for air.

A Cryptoclidus combs through the sand to eat stones. These act as ballast, weighing him down. At sunset, a group of Cryptoclidus is on the land, both to sleep and to be safe from predators.

At night, a host of microscopic animals attracts shoals of fish and squid, which are in turn hunted by the Ophthalmosaurus, which have excellent vision. The beach is meanwhile visited by hordes of horseshoe crabs. These extremely ancient arthropods have come to lay thousands of eggs each.

In the morning, the Cryptoclidus swim back into the ocean. The horseshoe crabs, still retreating into the water, have their eggs pillaged and eaten by flocks of Rhamphorhynchus. The pterosaurs are in turn attacked and eaten by multiple Eustreptospondylus. A month later, the hatching horseshoe crabs are swept into the sea by the tide.

The Ophthalmosaurus pups have grown large enough to survive in the open ocean, and are beginning to learn to hunt fish in open water. The sharks are still a threat, though.

The old Liopleurodon goes up for a gulp of air, and waits in the depth for a shark ambush, where he can hold his breath for an hour. However, a female Liopleurodon arrives, and the two territorial reptiles fight violently. The male, flipping the camera, tears the female's flipper. As she bleeds, she is followed by groups of Hybodus.

Four months after the Ophthalmosaurus pups' births, a violent tropical storm ravages the ocean. Although most of the Ophthalmosaurus pups survived the storm, hundreds of marine animals are killed, as are flocks of Rhamphorhynchus. The old Liopleurodon has stranded himself on one of the island beaches. A pack of Eustreptospondylus show up - as he is still a danger whilst alive, they wait for him to suffocate before devouring him.

Cast and crewEdit

Animals featuredEdit





On IMDb, Cruel Sea has a rating of 8.2/10, based on 87 user reviews and one critic review.

Cruel Sea has been criticised for presenting Liopleurodon as being 25m, larger than the largest known fossils which scientists have decided to assign to the species.

Technical errorsEdit

As the Eustreptospondylus hustle over the remains of the sea turtle, you can briefly notice the leg of the puppeteer on the right side of the screen, during one of the closeups of the animal's head.

In the opening shot in which we see the head of a Eustreptospondlyus through the water, a dark object can be seen above its neck at certain points.

When the Ophthalmosaurus is giving birth, it is evident that the animatronic used in this scene is being damaged by the water - bits of "skin" are falling off, revealing whitish rubber underneath. The small, protruding bulges on the belly of Ophthalmosaurus in some quick shots reveal where the mechanical attachments are connected to the Ophthalmosaurus model.

The blue-screen effect of the Ophthalmosaurus pup has been rendered incorrectly, as evidenced by the strange blue spots that run along its body, through which you can actually see the objects in the background. This effect makes the animal seem transparent.

After the Cryptoclidus plunge into the water, they briefly become see-through.

Availability and broadcastingEdit

Cruel Sea first aired on Friday 30th April 1999, on BBC One. It features on every DVD release and boxset of Walking with Dinosaurs.