On November 8, 2023, a marine research team led by Kostas Toktaridis of ROV Planet Blue found the remains of the French submarine Floreal, sunk in 1918 during World War I in the waters of the Thermaic Gulf (also known as the Gulf of Thessaloniki), northeast of Greece.

The Floreal belonged to the Pluviôse class of the French Navy, considered the first generation of submarines with true operational capability.

It was designed by naval engineer Maxime Laubeuf and incorporated innovations for the time such as a double hull and a dual propulsion system.

On August 2, 1918, the Floreal set sail from Thessaloniki escorted by the destroyer Balliste heading to Patras, Greece.

However, during the night, it collided with the British ship HMS Hazel while it was zigzagging to avoid possible attacks by enemy submarines.

Despite rescue attempts, the damage was so severe that the Floreal ended up sinking at 03:25 in the Thermaic Gulf. Fortunately, its crew of 25 sailors was rescued alive.

The location of the submarine wreckage was the result of several years of archival research in French and British historical sources. In 2014, Greek diver Spyros Vougridis initiated the search for the wreck with a research team.

In 2023, they managed to find the target thanks to sonar surveys and visual confirmation through a remotely operated underwater vehicle or ROV.

The remains of the Floreal lie at a depth of 98 meters, in excellent condition. Its design and features fully match historical documentation, allowing for its identification without a doubt.

The unmistakable silhouette of the bow, torpedo tubes, and details such as a partially open hatch transport the viewer back a hundred years.

The discovery of the first sunken war submarine in Greek waters during the Great War holds great historical significance. It will enable the study of naval engineering from the early 20th century and commemorate the sacrifice of allied sailors who risked their lives in submarine warfare.

The well-preserved wreckage also promises to provide valuable information about life aboard these pioneering submarines.


Kostas Toktaridis (Facebook) | Planet Blue History (Youtube)

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