Underwater Archaeology

Underwater archaeology is a sub-discipline of archaeology that investigates human history through material remains submerged underwater. While sharing the fundamental principles and objectives of terrestrial archaeology, it differs by employing specialized methods, techniques, and equipment required by the underwater environment.

Underwater archaeology encompasses not only shipwrecks but also architectural structures such as cities, harbors, and bridges that have become submerged due to earthquakes, changes in water levels, or human activity, as well as any object deliberately placed or accidentally dropped into aquatic environments.

Terminology and Sub-Disciplines

Underwater archaeology is divided into various sub-disciplines based on the nature of its research area and the types of artifacts studied. These sub-disciplines may sometimes overlap in their areas of investigation.

• Nautical Archaeology: Focuses on the construction technologies, designs, historical development, routes, and cargoes of ships and boats. It examines both submerged and terrestrial shipwreck remains.

• Maritime Archaeology: Studies all human interactions with seas, lakes, and rivers. It is a broader field that includes nautical archaeology and also covers harbors, maritime trade, naval warfare, maritime culture, and economy—not just vessels.

• Coastal and Wet-Site Archaeology: Investigates settlements that have become partially or fully submerged due to various causes. These sites can provide valuable data, particularly regarding the preservation of organic materials.

• Lake and Riverine Archaeology: Concentrates on archaeological remains in lake and river environments. Structures such as harbor and bridge remnants along riverbanks or lake dwellings fall within this field.

• Deepwater Archaeology: Encompasses research conducted at depths beyond the limits of human diving, typically using remotely operated vehicles (ROVs) or autonomous underwater vehicles (AUVs).

• Wetland Archaeology: Examines archaeological sites in waterlogged environments such as marshes, deltas, and peat bogs. These areas offer high preservation levels of organic finds due to anoxic (oxygen-free) conditions.

• Foreshore Archaeology: Studies archaeological remains in coastal zones that are periodically submerged and exposed due to tidal movements. It is a particularly common research area along ocean coastlines.

• Treasure Hunting: An activity driven by financial gain rather than scientific objectives. It conflicts with the core principles of underwater archaeology due to its damage to archaeological sites and destruction of historical context.

Historical Development

The development of underwater archaeology as a scientific discipline has progressed in parallel with advances in diving technology. Early underwater investigations, initially conducted for antiquarian or treasure-hunting purposes, gradually adopted a scientific framework. The development of modern diving equipment such as SCUBA enabled archaeologists to conduct more effective and prolonged underwater research. These technological advances led to the adoption of an approach that emphasized not only the recovery of artifacts but also their documentation and interpretation using scientific methods, shaping the discipline’s current identity.

Global Developments

Interest in underwater remains began with traditional divers such as sponge fishermen discovering ancient objects. The first technological steps were taken with diving bells used since the 16th century. In the 19th century, the diving helmet developed by Augustus Siebe allowed for longer underwater work and facilitated the first systematic artifact recovery operations, such as those conducted on vessels found in the Nydam bog in Denmark.

The origins of underwater archaeology as a scientific discipline date to the mid-20th century. The Antikythera Shipwreck, discovered in 1900 by sponge diver Elias Stadiatos, is among the first major finds recovered from underwater. However, the pivotal turning point was the invention of modern SCUBA (self-contained underwater breathing apparatus) by Jacques-Yves Cousteau and Émile Gagnan in 1942–43. This invention enabled archaeologists to work more freely and for extended periods underwater.

The first scientific underwater excavation directed by an archaeologist was conducted by George F. Bass in 1960 at the Cape Gelidonya shipwreck in Türkiye. This excavation established underwater archaeology as a scientific discipline and laid the foundation for modern methods. This development was followed by the establishment of academic publications such as the International Journal of Nautical Archaeology (IJNA) in 1972 and specialized institutions such as the Institute of Nautical Archaeology (INA).

Developments in Türkiye

Türkiye possesses significant potential for underwater archaeology due to its geographical location and rich maritime history. Scientific work in the country began in 1960 with the excavation of the Middle Bronze Age shipwreck by George F. Bass and his team. This excavation is regarded not only as a starting point for Türkiye but also as a landmark in global underwater archaeology. The artifacts recovered from this dig formed the foundation of Türkiye’s first underwater archaeology museum, the Bodrum Museum of Underwater Archaeology.

Subsequent excavations included the Yassıada Byzantine Shipwreck, the Serçe Limanı Shipwreck, and the Uluburun Shipwreck dated to the 14th century BCE. These studies initially focused on the Mediterranean and Aegean coasts; from the 1980s onward, research expanded to the Sea of Marmara. Institutions actively involved in Türkiye’s underwater archaeology include INA, TINA (Türkiye Sualtı Arkeolojisi Vakfı), Ankara University Center for Underwater Archaeological Research and Application (ANKÜSAM), and the 360 Degrees Historical Research Association.

Methods and Techniques

Unlike terrestrial archaeology, underwater archaeology has developed specialized methods to address challenges posed by water’s buoyancy, limited visibility, pressure, and currents.

Survey and Prospection

Researching an underwater area involves a multi-stage process of discovery and identification. This process typically begins on land with archival research examining historical texts, maps, and ship records. This theoretical foundation is supplemented by local knowledge gathered from fishermen and sponge divers, providing initial leads on potential sites. Following these preparatory steps, the first phase of underwater work involves visual surveys, during which divers systematically search the area using patterns such as circular or “U”-shaped sweeps to identify surface remains.

For large or deep areas, remote sensing and geophysical methods are employed. Side-scan sonar generates an acoustic map of the seafloor to detect surface anomalies. Magnetometers are used to locate metal objects such as shipwrecks, while sub-bottom profilers detect objects buried beneath sand or silt. In depths inaccessible to human divers, ROVs (Remotely Operated Vehicles) are used for visual inspection. All these methods are used to precisely locate potential archaeological sites and prepare the groundwork for excavation.

Excavation

The excavation phase involves the systematic recovery of archaeological finds from identified sites. Before work begins, the excavation area is divided into a grid system using ropes or metal frames to precisely record the location of each artifact. This system enables the recording of three-dimensional (x, y, z) coordinates of every find, preserving its scientific context.

After the area is organized, surface sediments such as sand, silt, or debris are carefully removed using tools designed for underwater conditions. Airlifts and water dredges, which operate via a pipe system and function like underwater vacuum cleaners, remove sediment in a controlled manner. In larger areas, the prop-wash technique—directing water currents generated by a boat’s propeller—may be used to disperse sediment. Every stage of the excavation is documented.

In addition to photographic and video documentation using underwater cameras, photogrammetry is used to create three-dimensional digital models of the site. Divers also make immediate records by drawing on waterproof plastic sheets. This systematic approach enables the examination and scientific interpretation of finds without disturbing their original context.

Conservation

Artifacts recovered from underwater environments can undergo rapid deterioration upon exposure to new conditions; therefore, conservation is a critical phase of excavation. To prevent organic materials such as wood, leather, and textiles from drying, cracking, or disintegrating, the wet storage method is applied, keeping these materials continuously moist. Additionally, desalination—the controlled removal of dissolved salts through freshwater baths—is vital to prevent internal damage during drying. Finally, a consolidation process involving chemical treatments strengthens the material structure; for example, polyethylene glycol (PEG) is commonly used to stabilize waterlogged wood.

Protection and Presentation of Underwater Cultural Heritage

Underwater cultural heritage faces threats from treasure hunting, illegal salvage, trawling, and pollution. International and national regulations and approaches have been developed to protect this heritage and make it accessible to the public.

• Legal Framework: The 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage is the most comprehensive international document in this field. It prioritizes scientific research and in-situ preservation over commercial exploitation.

• Museums: Artifacts recovered from underwater excavations are displayed in specialized museums such as the Bodrum Museum of Underwater Archaeology. These institutions ensure the preservation of artifacts and play a key role in sharing cultural heritage with the public.

• Underwater Archaeoparks and Museums: This approach, based on the principle of in-situ preservation, involves transforming archaeological sites into underwater parks or museums accessible to visitors. These sites can promote cultural heritage awareness and contribute to local economies through diving tourism. The Baiheliang Underwater Museum in China is a structure built around a preserved in-situ inscription. In Türkiye, archaeological park projects have been developed in areas such as Kaş and Mordoğan, displaying replicas of original shipwrecks. Such projects enable public access to cultural heritage while protecting the original sites.