You may not realise it, but lurking under the waves of Chichester Harbour lives an incredible wealth of colourful marine life, from sea squirts and sea anemones to pipefish and crabs.
The stunning array of creatures and plants living in their underwater world has now been captured on camera by a team of divers who couldn't believe their eyes.
They saw colourful seaweeds, reefs of oysters providing a home for bright-red sea squirts and sponges, and strange alien-looking cuttlefish with 'zebra stripes'.
The divers found the harbour teeming with carnivorous anemones which have stinging cells for defence and capturing prey which includes small marine animals such as shrimp, prawns and even small fish.
There are even large predators hiding under the shore, including harbour seals and smoothounds, which belong to the hound shark family.
Four divers were carrying out an extensive sub-tidal survey for Chichester Harbour Conservancy, which was funded by the Heritage Lottery Fund. They spent five days in July 2006 exploring the marine environment.
They were stunned at the clarity of the waters and the creatures they discovered, and were able to bring back clear images and video footage of the species. The sub-tidal survey was carried out by Seascape, a marine environment consultancy firm, which until six years ago was based in West Sussex.
The divers used expert scuba-diving equipment, underwater cameras and specimen-collecting bags.
Seascape principal consultant and one of the divers, Robert Irving (51), said: "I've done some diving in the harbour before, but this time was more extensive.
"We were surprised by the diverse nature of the harbour life – it was far richer than we could have imagined."
The survey revealed the harbour is crowded with more than 220 different species of marine life, some rare and unusual ones.
The divers recorded 34 habitat types, showing the sheer variety of the sea bed.
The harbour beds are unique in Sussex and provide a sheltered nursery for juvenile fish, crabs and other species.
Chichester Harbour Conservancy Area of Outstanding Beauty and countryside officer Nicky Horter said: "It was a real eye-opener. Not only was it the first time we have had a really comprehensive survey conducted of the harbour, but what was found was just fantastic.
"The footage reveals the variety of life in the harbour waters.
"It is stunning to see all the plant life, fish and shellfish. The video shows what a fascinating marine environment we have."
Chichester Harbour is within an Area of Outstanding Natural Beauty, while the Chichester Harbour Conservancy has a legal duty to manage the harbour for recreation, leisure and conservation.
The survey was considered an expensive project, costing in the region of 23,000, but a marine survey of this type is carried out only every five to ten years, and is important to monitor the diverse sub-tidal environment.
For more information and videos on Chichester Harbour, click here.