Following on from the hugely successful Walking With Dinosaurs and Walking With Beasts, Sea Monsters was screened by the BBC in 2003 and featured Nigel Marvin taking a dip in the seven deadliest seas of all time.

As in the previous features, Crawley Creatures provided their expertise in many of the episodes.

Jez Gibson-Harris (right) outlines some of the creatures made for the show and describes some of the difficulties in filming as well as some of the ingenious solutions to a variety of problems!

Filmed in Egypt, the episode on the Ordovician Seas saw a sea scorpion, a trilobite, an armored fish called an astrapsis and a huge set of jaws from a megaladon travel from the Crawley Creatures workshop in Aylesbury.

The Sea scorpion was a very complex creature to build, sculpted by Colin Shulver and mechanized by Tamzine Hanks. The creature was completely self contained with on board batteries and all the electronic components had to be waterproofed and resistant to salt water.

On this show the salt water was always going to be the biggest challenge. Finding materials that would stand up to being in strong sunlight and heat on land, be flexible and retain their painted surfaces and not corrode quickly in salt water and electronics that could be protected in the very corrosive environment was a difficult task

The large Megalodon jaws we made were eight feet tall and made of jesmonite and tissue matt. They were constructed in four sections as they had to be carried on the aircraft with us to Egypt and took us several hours of haggling to get them through customs!

The episode on the Devonian Seas saw us travel to New Zealand with another armored fish called bothriolepsis. This model fish was made as a free swimming animatronic that worked off a heavily waterproofed Makita battery drill, which after a while in the water the switching mechanism suffered and the drill sped up and we struggled, on the deck of our 80ft Ketch, to turn off as it thrashed around!

For the Triassic episode we made a nothosaur (left), eggs and nest and filmed on location in New Zealand and the Bahamas.

We purchased a pair of Farrallon diving aids (6ft torpedoes with a propeller driven by huge 12volt batteries) The two tubes where attached to a sled and formed the basis of our underwater driving system for the Nothosaur, Archelon and Megalodon. Two divers were required one to steer the creature and one to operate the cable controls to open the eyes, mouth head and neck mechanisms.

The Nothosaur was a foam latex skinned model which, after diving to twenty feet came up looking rather crushed (by the pressure).

The Jurassic episode required us to create a 2.5 metre long scale model of leedsichthys, which in real life was 80 feet long. Leedsichthys in life was 80ft long and because of the interaction required, CG sharks and Liopleurodons attacking and eating it, the Director and Series Producer, Jasper James, wanted a 1/10th scale model making, that we could film in a tank where we would have more control of the movements and create the weight and feel of a giant fish under attack.

For the Cretaceous episode we built a three metre front section of the giant turtle, Archelon. We only required the front half as we needed Nigel Marvin to dive down and swim with the turtle as it swam near to the surface in the beautiful clear waters of the Bahamas.

Later in the story, the remains of the turtle awaken the crew as it bangs against the side of the boat after having been bitten in half by a giant predator. The turtle was attached to our Farrallon rig and operated by four divers. The turtle had a polyurethane rubber skin and a GRP (fibre glass) shell. Both had been pre-coloured and worked very successfully.

One morning, out of the blue, the Director said that he required a huge ‘bait/chum ball’ for the following morning. We had very few materials available but they included a very small kit of two part polyurethane foam, a large plastic dustbin from the dive centre. That became the core of the chum ball and was filled with weights.

The two part foam was used to adhere torn pieces of furniture foam, dead fish from the boat dock and anything else that came to hand to the bin. Once the dustbin was covered the whole was painted a dark blood red. When the Director came ashore from the days shooting he was very impressed. The next day the bin was filled with fake blood and filmed in the water.

We ran out of blood repeatedly as we had been given no idea of the requirement. So we roamed the Bahamas and bought up vast amounts of food colouring, Grenadine syrup and maize syrup to make up gallons of fake blood.

The Pliocene episode was filmed across locations in Egypt, New Zealand and the Bahamas. We built a megalodon shark fin consisting of a four metre GRP section of back with a two metre tall polyurethane rubber fin, it was required that the tip of the fin should be flexible like a Great White shark and allow for a harpoon to be stabbed into it. When the fin arrived in New Zealand it was driven to our location on the back of a truck to our location in the north of the North Island.

Myself and Physical Effects Supervisor, Jamie Campbell and two New Zealand divers spent four days building a scaffolding rig that was slung under the back section, seats were made for two diver operators that would operate dive planes and plywood hydrofoils were made from some bent wood, found outside our hotel, to stabilize the fin and finally buoyancy was added.

Then we did our sea trials; towing the fin with the two divers under it behind a dive boat. The divers were able to raise and submerge the fin using the dive planes. When it came to filming we were able to tow the fin out to the location about eight miles away by getting the speed of the dive boat right we could get the fin rising out of the water on the, highly effective/cobbled together, hydrofoils.