Researchers mapping ancient submerged landscapes in the Bulgarian waters of the Black Sea have stumbled upon a shipwreck graveyard with dozens of perfectly preserved vessels from the Ottoman and Byzantine periods.

Led by the University of Southampton's Center for Maritime Archaeology and funded by the charitable organization Expedition and Education Foundation (EEF), the Black Sea Maritime Archaeology Project was carrying out a survey to understand how and when the water level rose in the Black Sea following the last Ice Age.

The researchers came across a spectacular collection of 41 shipwrecks while scouring the seabed with some of the most advanced underwater survey systems, including a revolutionary Remotely Operated Vehicle (ROV) which set new records for both depth (5,905 feet) and sustained speed (over 6 knots).

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"The wrecks are a complete bonus," Jon Adams, founding director of the University of Southampton's Center for Maritime Archaeology and principle investigator on the project, said in a statement.

"They are astonishingly preserved due to the anoxic conditions (absence of oxygen) of the Black Sea below 150 meters (492 feet)," he added.

All the ships sank far out at sea, likely because of storms and rough seas.

The wrecks provide new information on the Black Sea's maritime traffic. They include a Medieval vessel never before seen so complete, and a ship from the Ottoman period with coils of rope still hanging from its carved timbers.

"We've been able to capture some astonishing images without disturbing the sea bed," Adams said.

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To do so, the team used photogrammetry. The technique relies on software which calculates the 3-D positions of millions of points in space — in this case from thousands of photographs.

The result is a vessel model rendered and overlaid with the colors and textures from the photos, which produce the most accurate representation.

"We are now among the very best exponents of this practice methodology and certainly no one has achieved models of this completeness on shipwrecks at these depths," Adams said.

Here are some spectacular images of the wrecks:

Photogrammetric model of a medieval shipwreck. Credit: Rodrigo Pacheco Ruiz/ EEF - Expedition and Education Foundation

Compiled using extremely high resolution photographs taken by cameras on the ROV, this photogrammetric model represents the first and most complete image of a type of a Medieval ship which was previously known only from a few fragmentary archaeological finds.

Photogrammetric model of a Byzantine wreck with Surveyor ROV. Credit: Rodrigo Pacheco Ruiz/ EEF - Expedition and Education Foundation

This Byzantine wreck was discovered 311 feet below the surface. The image shows the ROV passing over the ship to gather 3-D data.

Photogrammetric model of stern of Ottoman shipwreck. Credit: Rodrigo Pacheco Ruiz/ EEF - Expedition and Education Foundation

This is a detail of the stern of an Ottoman shipwreck discovered 900 feet underwater. The carved tiller lies by the stern post and rudder. The astonishing preservation of the organic materials is shown by the coils of rope still hanging from the timbers.