Miss Lyyli Karoliina Silvén was born in Tornio, Lappi, Finland on 11 June 1894.

She was the eldest child of Aleksanteri Nikolai Silvén (1870-1924), a customs officer, and Anna Karoliina Karjalainen (1859-1921).

Her known siblings were: Lilly Sofia (b. 1896), Bror Sigurd Aleksander (b. 1897), Lauri Johannes (b. 1900) and Johan Ferdinand (b. 1902).

Lyyli was leaving her native Finland and travelling to Minneapolis, Minnesota under the care of relatives, the Finnish-American couple William Lahtinen and his wife Anna, née Sylfvén. She boarded the Titanic at Southampton as a second class passenger (ticket number 250652 which cost £13). Whilst aboard she shared a cabin with another Finnish girl, Anna Siukkonen.

On the night of the sinking Lyyli attended a "dance" in second class but retired to her cabin and was asleep at the time of the collision. The impact wakened her and Miss Sinkkonen and Lyyli promptly left the cabin to find her relatives. She then returned to fetch Anna and prepare for the evacuation but before they could get fully organised a steward arrived and forced them out of their cabin. 

It appears that Lyyli and Miss Sinkkonen became separated and departed in different boats but this is not clear. Lyyli recalled that the Lahtinens were standing nearby on the boat deck, with Mrs Lahtinen appearing to be very nervous. Lyyli entered what she described as the 'last lifeboat', however it is believed she left in boat 12.

Upon her arrival in New York Lyyli and Anna Sinkkonen were quartered in a Jewish "Welcome Home" on 225 East 13th Street. She then travelled to Hancock, Michigan where her uncle Carl Albert Sylfvén, brother of Anna Lahtinen, and his family lived before moving on to San Francisco.

Lyyli was married around 1919 to widower Otto Wilhelm Mailanen (b. 21 June 1887), a Finnish carpenter originally from Turku who had emigrated in 1900; they would have no children. Otto's first marriage to Fiina Josefine Kaskela (b. 1885) had produced a daughter in 1912, Aune Josephine. Fiina died in 1916 and it appears that Lyyli raised Aune as her own.

Lyyli, her husband and step-daughter initially settled in Vallejo, California, appearing there on the 1920 census at 332 Kentucky Street, before moving to Berkeley, Alameda, California sometime before the onset of the 1930s and appearing on the 1930 and 1940 censuses as residents of 1430 Allston Way. By 1943, at the time of her husband's WWII draft registration, they were residing at 1321 Lincoln Street, Berkeley.

Lyyli would later return to Finland for a visit, twelve years after her departure; another visit in 1939 saw the onset of the Winter War.

Widowed on 6 January 1967, Lyyli continued to live in Berkeley until her own death on 5 February 1974. She and her husband are interred in El Cerrito Cemetery in Berkeley.

Her stepdaughter Aune was married in 1946 to Bryce Leon Beckham (1920-1982) before she divorced and remarried in 1953 to Benjamin Sigwalson Neally (1908-1953) but that marriage lasted less than a year and she was widowed. Another marriage occurred in 1955 to Lawrence James Colgan (1918-1966). What became of her thereafter is not certain.