FLOAT out beyond the Crusader city walls, Roman aqueduct and 19th-century mosque. Then descend through a cloud of quicksilver bubbles 20ft and 2,000 years to Herod The Great’s sunken harbour.

Here, just off Caesarea port, a unique underwater archaeological park opened yesterday, showcasing 80,000sq m of a sunken harbour built by the biblical king of the Jews for Caesar Augustus.

It is no ordinary “museum” — no chattering schoolchildren, no queues, no headphones, and the only sound that of boat propellers passing above your head as you swim around the “exhibits”.

“I am excited. I think anyone in the field of maritime archaeology would be,” said Dr Nadav Kashtan, a lecturer on ancient marine civilisations at Haifa University and one of the team who has brought the idea to life, with £60,000 from the Caesarea Development Corporation.

“If a museum is only dead showcases, then you do not attract the young audience, which is the main type of person you want to come.

“Bringing people into the real, wet experience is something very special.”

The brainchild of his former colleague Avner Raban, who died before seeing it realised, the park’s aim is to make available to amateur and professional divers the construction techniques used by Herod’s workers and Roman engineers to build the ancient port. In a dim green light beneath the waves, guides with waterproof maps lead divers along a marked route around the harbour foundations and sunken ships left on the seabed from 2,000 years of Phoenician, Roman, Jewish, Crusader, Byzantine, Mameluke and British history.

Forty miles (64km) north of Tel Aviv, the park is divided into four diving complexes with 36 stops. One of the four routes can be viewed from the surface by anyone with a snorkel. The other three can be reached only with diving equipment.

Anyone expecting the bright coral or abundant fish of the Red Sea would be disappointed amid the huge blocks of grey-green Herodian foundations.

But for archaeologists, historians or anyone with a passing interest in Levantine history it is a rewarding and technically simple dive.

During a 53-minute tour down to 20ft (6m) The Times saw exhibit 10, metal sheets of a steamer sunk in 1950 as a breakwater for the modern quay; exhibit 11, an Herodian quay of ashlar slabs; exhibit 12, a later Roman shipwreck; exhibit 13, six anchors; and 14, the Prokumatia, the narrow wall of an Ancient Roman breakwater.

The structures have been colonised by glassworms, molluscs and brick-red sponges matching the colour of the ancient shards of pottery.

Farther out divers inspected remains of a lighthouse, promenade, loading piers and statue pedestals. The park’s founders insist that the remains confirm historical accounts of Flavius Josephus, the 1st-century Jewish historian.

He hailed the magnificence of Herod, who also built Jerusalem’s second Jewish Temple of biblical antiquity. “The king ordered the building of many structures of white stone. He glorified the city with palaces pleasing to the eye,” Josephus wrote. Caesarea, built by Herod between 22BC and 10BC, was the Roman capital of Judea for 600 years. It was named after Caesar Augustus, who provided the money and engineering expertise.

But the decades of hard work, importing special volcanic rock from Vesuvius for the foundations, was destroyed after only a century when an earthquake damaged the harbour in AD130. It fell into disuse from the 4th century.

The first modern survey of the ruins was by the Palestine Exploration Fund in 1873 using a Royal Engineers team. It included a young Lieutenant Horatio Kitchener, later Lord Kitchener. He was nearly killed in an ambush near Safed during a Western Palestine survey.

Times Recommends

• UN may halt 400-year-old 'freedom of the seas'
• Where the Rosetta belongs can’t be set in stone
• Gas deal on hold, but Ukraine may pay in the end