Using state-of-the-art sonar equipment, an Estonian naval vessel last week located the wrecks of HMS Cassandra, HMS Gentian and HMS Myrtle near the Estonian island of Saaremaa, about 90 miles (140 kilometers) southwest of the capital, Tallinn.
"We are convinced that these (wrecks) are ... those perished British vessels," Cmdr. Ivo Vark said in a statement.
He said that the last coordinates of the vessels — reported by then British squadron commander Adm. Edwyn Alexander-Sinclair — were "surprisingly accurate" and helped the search substantially.
The light cruiser HMS Cassandra sank on Dec. 6, 1918 after hitting a mine, killing 10 sailors in a blast, Estonian naval officials said. The remaining crew of 400 was evacuated.
Minesweepers HMS Gentian and HMS Myrtle both sank on July 15, 1919 after hitting mines while on routine clearing missions. A total of nine sailors were killed in the two blasts.
The three vessels were part of British squadrons sent to the Baltic Sea in 1918-19 to extend support and deliver arms to the newly created state of Estonia, which was fighting for its independence against both Soviet Bolsheviks and German troops.
Naval officials said the HMS Myrtle had been spotted in 1937, while the location of the two other vessels remained a mystery until now.
The wrecks lie at depths of up to 100 yards. Estonian officials did not elaborate on the condition of the wrecks but said they legally belonged to Britain.
In recent years, numerous World War I and World War II-era wrecks have been found in the Baltic Sea.
(This version CORRECTS spelling of "surprisingly" instead of "surpassingly.")