Sea monsters book cover

Though the special itself did not have a logo, the companion book has a memorable cover.

Sea Monsters: A Walking with Dinosaurs Trilogy
features Nigel Marven as a presenter and team leader of the crew of the 'Ancient Mariner', ketch class ship - visiting the seven most dangerous seas of all time, starting at the seventh and ending with the most dangerous sea of all time.


Sea MonstersEdit

Main HazardsEdit

7. Giant Orthocone

6. Cymbospondylus

5. Dunkleosteus The fifth deadliest sea predator ever.

4. Basilosaurus  The fourth deadliest sea predator ever to exist.

3. Megalodon]] The third deadliest sea predator ever to exist.

2. Liopleurodon The second deadliest sea predator ever to exist.

  1. Tylosaurus]] The first deadliest sea predator ever to exist.

The Seven SeasEdit

The Seventh Most Dangerous SeaEdit

In his first journey to the seas, Nigel goes to the Ordovician to find a Giant Orthocone, and tangles with some sea scorpions in the process.

The Sixth Most Dangerous SeaEdit

Nigel travels to the Triassic, encountering Nothosaurus, Tanystropheus, and Cymbospondylus.

The Fifth Most Dangerous SeaEdit

This time Nigel heads back to the Devonian, and places a bet against his crew that a Dunkleosteus could rip through an armor-plated fish---when it was wrapped in chain mail.

The Fourth Most Dangerous SeaEdit

Nigel goes to the Eocene and finds the one of the nastiest ancient whales of all time, Basilosaurus, as well as some other surprising creatures, including Dorudon and Arsinoitherium.

The Third Most Dangerous SeaEdit

In the Pliocene sea, Nigel meets the largest predatory fish who ever lived and they find out what Megalodon hut, namely large whales. They also meet the bizarre Odobenocetops, what juvenile Megalodons hunt.

The Second Most Dangerous SeaEdit

Before Nigel heads toward the most dangerous sea of all, he decides to swim with a pair of Liopleurodon digging into a corpse of Leedsicthys and make it out alive.

The Most Dangerous Sea Of All TimeEdit

Nigel Marven nicknamed this sea 'Hell's Aquarium', due to the fact it was the most dangerous ever. As well as Tylosaurus, Elasmosaurus and Archelon and many other creatures can be found in this sea.


There are 3 episodes.

[edit]Episode OneEdit

[edit]The Seventh Most Dangerous Sea of All TimeEdit

Name: The Ordovician
When: 450,000,000 BC
Hazards: Giant Orthocone, Sea Scorpion

In the Ordovician, the day is only 21 hours long and there is more carbon dioxide than in the 21st century, forcing Nigel to don a medical-looking backpack filled with air tanks with a special oxygen mixture. To attract a Megalograptus, Nigel finds the corpse of a dead armor-plated fish washed up on the beach. Because there is no land life, there are no coastal scavengers to eat what the sea spits out. Before long, Nigel wades into shallow water and the armor-plated fish attracts a large Megalograptus. The creature devours the armor-plated fish, before attacking Nigel's foot, cutting it badly.

Later on, Nigel attempts to go after a Cameroceras by removing the eye of a dead trilobite and replacing it with a small video camera. He then uses the inflatable raft to venture out into the deeper waters, where he throws the trilobite video camera combo overboard. However, aMegalograptus is quickly attracted to it, and Nigel immediately gets it off of the trilobite. Later in the afternoon, a Cameroceras grabs and eats the trilobite, and Nigel and the cameraman plunge overboard to film it. On the dive, Nigel wears a chain mail suit, so that any marauding sea scorpion cannot harm him. He finds the Cameroceras in which he watches it devour two Megalograptus. The Cameroceras is more agile in the sea than Nigel, and as it attempts to swim away, Nigel grabs onto its shell. When the Cameroceras starts to dive down into the depths, Nigel swims away to the surface, almost getting attacked by another Megalograptus. When Nigel pilots the boat back to shore, he finds a surprise: there are large numbers of Megalograptus mating in the shallow waters. Nigel manages to make his way safely through the Megalograptushoardes, but a few clamber onto the inflatable boat and puncture it.

[edit]The Sixth Most Deadly Sea of All TimeEdit

Name: The Triassic
Time: 230,000,000 BC
Hazards: Nothosaur, Cymbospondylus

As Nigel walks along the tropical coastlines of Triassic Switzerland, he explains that the reptiles are taking over the surface of the earth from the skies (e.g. Peteinosaurus), to the land (e.g. Coelophysis). But of course, he is here to see the earliest sea reptiles.

From the deck of the Ancient Mariner, Nigel and crew watch as a Nothosaurus comes up for air. When he sees one, Nigel dives into the seas, pursuing the elusive sea reptile.

Before long, Nigel finds a pair of Nothosaurus. The Nothosaurus circle him, and Nigel has his prod ready to put off any Nothosaurus that comes too close. One of the Nothosaurus move in closer, so Nigel grabs it around its head to swim with it, and he explains that he would be able to open and close its jaws with tremendous force, but the Nothosaurus' jaw muscles are very weak. Therefore he can ride with it without the Nothosaurus struggling . He lets the Nothosaurus go so that it can breathe air, and Nigel discovers another bizarre sea reptile: a female Tanystropheus.

Nigel follows the Tanystropheus, and attempts to get a closer look at her by grabbing onto her tail, impeding its movement. However, theTanystropheus loses her tail, similar to the modern day leopard gecko. Nigel can hold onto the tail only with difficulty, because it is thrashing around (intended as a predator deterrent). Suddenly the tail is snatched up and then eaten by a Cymbospondylus.

The Cymbospondylus begins to circle Nigel with glee, and he explains that its slow movement is designed to deceive prey, and it can move very quickly when it is needed to. After he pokes it with the prod several times, the Cymbospondylus swims away, and Nigel returns to the relative safety of the Ancient Mariner.

[edit]The Fifth Most Dangerous Sea of All TimeEdit

Name: The Devonian
Time: 360,000,000 BC
Hazards: Dunkleosteus

On a preliminary dive, another crew member of the Mariner (Mike) films a huge female Dunkleosteus, swimming around the shallow reefs near the Ancient Mariner. The crew springs into action, and Nigel goes fishing for Bothriolepis. Nigel places a bet with one of the other crew members that the Dunkleosteus will be able to slice through the Bothriolepis wrapped in the chain mail suit he used in the Ordovician. When the round shark cage is fully assembled, Nigel descends into it. The smell of the dead Bothriolepis begins to attract a young Stethacanthus. Eventually, the monstrous Dunkleosteus is sighted, which scares away the Stethacanthus, and the enraged fish repeatedly bashes the cage with its thick head, and looks as though she's about to rip a hole in the cage...

[edit]Episode Two: "Into the Jaws of Death"Edit

...However, the enraged fish only slightly dents the cage.

Eventually, Nigel throws the Bothriolepis out of the cage, and the Dunkleosteus slices through the chainmail and the Bothriolepis. Spying a young Dunkleosteus, the huge adult turns cannibal and kills the baby. She then regurgitates the indigestible parts of its meal (the armor plating and the chainmail).

As Nigel departs for the surface, he explains that the placoderms as a whole have a grim future ahead of them. In another twenty million years, the entire Class of Placoderms will disappear, much to the other Devonian fish's relief.

[edit]The Fourth Most Dangerous Sea of All TimeEdit

Name: The Eocene
Time: 36,000,000 BC
Hazards: Basilosaurus

While walking in the mangrove swamps of Giza, Nigel comes across some mysterious footprints and a mound of fresh dung, by smelling the manure, he proves that the owner is a fruit-eater. Following the tracks, Nigel comes across an Arsinoitherium migrating overland. Nigel takes a calculated risk and offers the huge fruit-eater an apple, but apparently this upsets the Arsinotherium and it charges at Nigel. Only by making a break into the thicker forests does Nigel escape from the mammal. Nigel watches from the forest as the Arsinotherium plunges into the water, and follows it. In the water, Nigel watches as a trio of Dorudon, a species of ancient whale, pass by, and he explains that whales are the reason he came: not for the Dorudon, but a far bigger and meaner whale, Basilosaurus.

The Ancient Mariner sails offshore, where the crew try a tactic to attract whales that has been used with mixed success: record a Basilosauruscall and play it back via a huge speaker that is lowered from the boat. After playing it for a while, an enraged Basilosaurus rams into the boat before diving again. Wasting no time, Nigel suits up and dives. However, the whale could attack from any direction, so Nigel stays close to the hull of the Mariner, using the boat like a shield to ward off the Basilosaurus. The Basilosaurus is evidently distressed by the calls, and attacks and disables the speaker (which is explained as a territorial response).

As the Ancient Mariner sails off forward through time, Nigel explains that the tropical Eocene is a world on the brink of great climatic change. As the Oligocene dawns, Basilosaurus, Arsinotherium and Dorudon will all vanish, victims of the climatic shifts that ended the Eocene, changing the warm sea into a cold ocean.

[edit]The Third Most Dangerous Sea of All TimeEdit

Name: The Pliocene
Time: 4,000,000 BC

As Nigel goes to the deep waters he need to put a camera on the Megalodon . His crew gets some bait ready and Nigel gets into the cage ready for the attack. Then from the deep the fierce Megalodon  comes to the cage and tries breaking it for the bait. He tries to get Nigel but he is not in the steel cage. Then quickly Nigel puts the camera on the megalodon and the team gives the bait to the megalodon and it swims away with its prize.

[edit]Episode Three: "To Hell... And Back?"Edit

When the crew of the Ancient Mariner head backwards in time, Nigel says that as the Ice Age begins, the whales that Megalodon preyed on migrated to colder waters, where Megalodon could not follow. Megalodon is doomed to extinction, by hunger.

[edit]The Second Most Dangerous Sea EverEdit

Name: The Jurassic
Time: 155,000,000 BC
Hazards: Liopleurodon, Metriorhynchus, Hybodus

Set around England, which was then largely underwater. This is the second most dangerous sea. Hazards include Liopleurodon, oone of the largest carnivorous reptiles of all time. Nigel spies a school of migrating Leedsichthys. One weaker one is lagging behind the school, and a nativeMetriorhynchus and a foreign Hybodus shark launch a joint attack. Using sonar, Nigel discovers that a huge Liopleurodon is heading toward the injured and dying Leedsichthys. The camera spots it circling the Leedsichthys which is already dead, though the Liopleurodon is eventually spooked away by the camera.

Nigel equips his and the cameraman's diving suit with a chemical system that will spray a cloud of deterrent at the huge pliosaur should they get too close. The crew use huge waterproof lights when they descend to the corpse of the Leedsichthys, because it is night. A pair ofLiopleurodon are feasting on the carcass, and Nigel starts to move closer toward them. When one turns its head towards him, Nigel panics and ejects the chemical, which works on the huge predator.

[edit]The Most Dangerous Sea EverEdit

Name: The Cretaceous/"Hell's Aquarium"
Time: 75,800,000 BC
Hazards: Xiphactinus, Sharks, Halisaurus, Tylosaurus/ Giant Mosasaurus


Nigel is now entering his final sea mission in "Hell's Aquarium" as he calls it. On the land there's T. Rex, but even the most famous land predator of time all can't compare to what's in the water. After viewing a colony of Hesperornis on the coastline, Nigel and another member of the Mariner pause for a second to view a huge underwater bloodbath. As far as Nigel (using a periscope) can figure out, an elderly Hesperorniswas killed, and the resulting carnage has attracted many sea animals, such as Squalicorax, and Xiphactinus. However, Nigel noticed another predator around: a mosasaur known as Halisaurus. Nigel had previously read about mosasaurs, and after spotting some of the smaller species, he and the crew headed out to deeper water in search of Tylosaurus. But Nigel explains that this sea is far too dangerous to go diving in; mosasaurs and other huge carnivores like Xiphactinus are far too dangerous. Instead, the crew of the Ancient Mariner have rigged an ROVto dive for them, while the sonar and cameras on the side of the boat would give them early warning if any mosasaurs are nearby.

The next morning, Nigel discovers that they have hit a dead Archelon, which was mauled by some other predator before being hit by the boat. Later, after managing to domesticate a Pteranodon, the sonar picks up some creatures right beneath the boat. This was a good time for them to use the ROV, and when they send it down, the crew finds that it's a small pod of Elasmosaurus riding their wake like 21st century dolphins, but soon they depart due to the risk that they may provoke the herd. Some of them knocked the ROV when they were investigating it, and anArchelon is also spotted. Having done the same thing with present-day leatherback turtles, Nigel forgoes his personal safety to track down theArchelon and ride it. He and the cameraman ride off in the small inflatable raft that they had used previously in the Ordovician.

Before long, Nigel finds the Archelon when it comes up to the surface for air. He dives, grabbing onto the huge turtle's shell. But not long after, the sonar picked up something nearby: a Xiphactinus was circling Nigel and the Archelon. He quickly makes his escape back up to the raft, but disaster strikes. A family pod of Tylosaurus attack and completely overturn the raft, plunging the crew into the sea. Fortunately for Nigel, the Tylosaurus seem more interested in the boat than the humans, and they quickly escape back to the Mariner.

During the credits, night falls and the crew is fast asleep while the sonar onboard picks up a colossal mob of adult Tylosaurus moving in from all sides, preparing to attack the ship.... their fate is unknown, but it is likely that Nigel and his crew escaped.

[edit]Animals of the TimelineEdit