The magnificent underwater remains of King Herod’s ancient harbor at Caesarea Maritima, which lay hidden for more than 2,000 years, can now be discovered by diving enthusiasts in a one-of-a-kind underwater park.

Inaugurated in April 2006, the park provides divers with the opportunity to view some of the world’s most extraordinary maritime ruins. A score of sign-posted sites guide divers along four marked trails within the 50-acre sunken Caesarea harbor, which includes remnants of breakwaters, basins, loading piers, storage rooms and a promenade. Ancient anchors and other isolated objects are also part of the underwater landscape.

Using a waterproof map, divers chart their own course while learning about the ancient world of the 2,000-year-old harbor and viewing the technological wonders of ancient harbor construction, as well as the ingenious building methods of Herod’s engineers, who built several of the most sophisticated port installations in antiquity.

There is also a trail that is accessible to snorkelers. All of the trails, which range from 7 to 29 feet below the surface, are suitable for beginning divers. Guided tours are also available.

While divers can view other underwater ruins elsewhere, they will normally have little idea of what they are seeing. The creation of the underwater park at Caesarea opens up a whole world of information about the ruins to underwater enthusiasts, said Dr. Nadav Kashtan, a maritime historian from the Department of Maritime Civilizations at the University of Haifa.

“This is really a unique underwater park, which has several characteristics of a museum—rare exhibits, panels with explanations, suggested visits—with one exception: A diving license is needed for a full visit,” said Dr. Kashtan.

The harbor, built by Herod with cutting-edge architectural techniques, was inaugurated in 10 B.C.E. as a major port for his kingdom. It reflected his relations with his patron, Emperor Caesar Augustus, whom he honored by naming the port Sebastos (Greek for “Augustus”) and the neighboring city Caesarea Maritima.

“The construction of the port signaled the transformation of the coast of ancient Israel into a region of international, cosmopolitan influence, related to the Roman empire and its maritime network,” said Dr. Kashtan. He noted that there were several ancient ports along the Israeli coast—in Acre, Dor, Jaffa and Ashkelon—but none that rivaled the size and significance of Sebastos, which was a “new gateway and stepping stone to relations between Judea and the Roman empire, serving as an economic and cultural center.”

The ability to build underwater was made possible during this time by the Roman invention of hydraulic cement, known as “pozzolana,” which the authoritative ancient architectural writer Vitruvius described as made of volcanic ash from the area of Naples and Mount Vesuvius. When mixed with limestone, sand and pebbles, the pozzolana hardened in water, said Dr. Kashtan.

Caissons (wooden, box-like structures filled with pozzolana) were sunk to create foundations for breakwaters, jetties and other constructions. The wooden caissons were covered by sand and rubble and were expected to disintegrate. Several of these caissons miraculously survived.

Caesarea Maritima was first systematically excavated in modern times at the beginning of the 1960s by Italian archaeologists and later by archaeologists from the Israel Department of Antiquities and The Hebrew University of Jerusalem, in cooperation with institutions from the U.S. and Canada. However, the main underwater research project was started in 1975 by the Center for Maritime Studies at Haifa University, under Professor Avner Raban, and continued until his untimely death in 2004. The Combined Caesarea Expedition, co-directed by Raban, Kenneth Holum of the University of Maryland and Joseph Patrich, now at The Hebrew University, renewed excavations at Caesarea Maritima. Professor Raban was the guiding force behind the idea of an underwater park, which he initiated in 1992. Unfortunately Professor Raban did not live to see his efforts come to fruition. Sarah Arenson, a former colleague of Raban and founder of the Society of Friends of Old Caesarea, has taken over the project following his death.

Also active in the rehabilitation and development of the sunken port into a park and museum were the Caesarea Development Company, the Caesarea Diving Center, the Israel Antiquities Authority and the Recanati Institute for Maritime Studies at the University of Haifa.—Judith Sudilovsky, Jerusalem