Imperial Russian submarine Akula (Russian: Акула - Shark) and armoured cruiser Ryurik, 1913

WW1 Russian submarine located by Estonian divers

The 400-ton Russian submarine, commissioned in 1911, was the biggest in the pre-revolutionary Russian navy. During the first world war, she served in the Baltic Fleet making 16 patrols and unsuccessfully attacked the German coastal defence ship SMS Beowulf.

In November 1915 during her 17th patrol, she struck a mine and sank near Hiiumaa with the loss of all 35 seamen and came to rest at a depth of about 30 meters.