Mankind’s thirst to uncover its past
The centuries-long isolation of the seabed heightens our expectations of exceptional discoveries—even more so than on land, where all remnants suffer greater degradation.
Scuba diving lets you uncover countless awe-inspiring objects. But in archaeology, discovery doesn’t mean retrieval. Here, discovery entails a study process—before and after the find—to explore and gather data about the site and objects, ultimately yielding historical conclusions. In short, it requires methodology.
Exploration comes at a high cost
Did you know the first underwater archaeologists were land-based professionals in the late 19th century? They hired sponge and coral divers to describe material remains spotted during dives. Much has changed since, yet the seabed and underwater archaeology remain surprisingly similar.
Archaeologists, who once paid others to see beneath the waves for them, now rely on sophisticated detection tools to explore remote—sometimes inaccessible—depths. Thus, they still pay to wrest secrets from the water. Whether through personal exploration or modern detection gear, funding an underwater archaeological project demands significant sums, often justified by political, economic, or scientific returns.
Documentation and surveying
Given these challenges, every project requires meticulous planning. After identifying a potential site and gathering documentation, on-site surveys begin.
Methods include visual exploration (divers or ROVs) and advanced detection tech. If the site warrants study, excavation follows—either immediately or in future campaigns.
What’s inside an underwater exploration?
Excavation initiates an irreversible process for extracted materials. Misinterpret their data, and it’s lost forever.
Each excavation differs based on environmental conditions, site characteristics, available resources, and diving expertise.
Most underwater excavations deploy specialised teams: divers, surface support, equipment handlers, and archivists for recovered artefacts.
Projects may target ship hulls, submerged buildings, or cargo. Regardless, the methodology must document each artefact’s position after removing layers of sand or sediment.
The excavation process
Once a site is demarcated, it’s mapped relative to land. Next, sediment layers are removed—techniques vary by site and lead archaeologist.
Tools range from hand-clearing to the iconic airlift, synonymous with underwater archaeology.
The airlift. This support tool is used after manual sediment removal. Never applied directly to the seabed, it suctions loosened deposits away from the work area, preserving critical data.
Powered by a surface compressor, it injects air through a tube into the airlift’s rigid base. Rising air creates suction at the tip, drawing in nearby material. Misuse can devastate a site—hence strict control is essential.
Underwater archaeologists work upside-down, leveraging aquatic buoyancy to avoid disturbing the site.
Cleared areas are documented via stereoscopic photography, video, or sketches for later reconstruction. Only then are artefacts extracted, numbered, and catalogued. The excavation process repeats layer by layer until completion.
Detection tools: a breakdown
Sophisticated (and costly) detection instruments include:
- Side-scan sonar. Torpedo-shaped, it’s towed behind boats, emitting high-frequency acoustic waves horizontally to create seabed images akin to aerial photos.
- Sub-bottom profiler. Uses low-frequency vertical soundwaves to penetrate sediments, revealing buried remains through echo variations.
- Proton magnetometer. Detects magnetic field distortions from ferrous metals—buried or exposed—indicating mass and depth.
Post-recovery
After documentation, multidisciplinary analysis begins: chemists conserve artefacts, biologists study organic samples, and others interpret each piece’s original context.
Findings are then shared—guided by political, scientific, or economic factors. Despite challenges, the underwater past gradually yields its jealously guarded secrets.
