In addition to his native Estonian, Lennart Meri fluently spoke five other languages: Finnish, French, German, English, and Russian.

Lennart Meri and his family lived in Tallinn when Estonia was invaded and occupied by the Stalinist Soviet Union in June 1940.

After a trip to the Tian Shan Mountains in Central Asia and the old Islamic centres in the Kara Kum Desert in 1958, Lennart Meri wrote his first book, which met with a warm reception from the public.

Already as a student, Lennart Meri had been able to earn his living with his writing, after his father had been arrested by the Soviet authorities for the third time.

Tulemägede Maale, created in 1964, which is translated as To the Land of Fiery Mountains, chronicled Meri's journey to the Kamchatka Peninsula in the 1960s.

Meri did not underestimate the drawbacks of mass tourism but concluded that "science will liberate us from the chains of big cities and lead us back to nature".

Meri's travel book of his journey to the northeast passage, Virmaliste Väraval (At the Gate of the Northern Lights) (1974), won him huge success in the Soviet Union.

In the book Meri combined the present with a perspective into history, and used material from such explorers as Cook, Forster, Wrangel, Dahl, Sauer, Middendorff, Cochran, and others.

Hõbevalge is based on a wide-ranging ancient seafaring sources, and carefully unveils the secret of the legendary Ultima Thule.

According to Meri, it is possible that Thule derives from the ancient Estonian folk poetry, which depicts the birth of the Kaali crater lake in Saaremaa.

In the essay Tacituse tahtel (2000), Meri examined ancient contacts between Estonia and the Roman empire and notes that furs, amber, and especially Livonian kiln-dried, disease-free grain may have been Estonia's biggest contribution to the common culture of Europe – in lean years, it provided seed grain for Europe.

In Estonia, environmental protests soon grew into a general revolt against Soviet rule: the "Singing Revolution", which was led by Estonian intellectuals.

Meri's speech Do Estonians Have Hope focused on the existential problems of the nation and had strong repercussions abroad.

He developed around him a group of well educated young people, many English speaking, to establish an open communication channel to the West, and at the same time to represent Estonia more widely on the international scene.

Meri made public remarks against the Karaganov Doctrine on 25 February 1994 in a festival speech to the good Hamburgers, who descended from the trade barons of the Hanseatic League.

[5][2] Karaganov generated his doctrine in about 1992, and it states that Moscow should pose as the defender of human rights of ethnic Russians living in the 'near abroad' for the purpose of gaining political influence in these regions.

[13] Lennart Meri was engaged in the work for the human rights of German refugees from Central and Eastern Europe and other victims of ethnic cleansing in Europe, and was a member of the jury of the Franz Werfel Human Rights Award, which was awarded by the Centre Against Expulsions (Zentrum gegen Vertreibungen).

The tumor was found to be malignant and he died on the morning of 14 March 2006, fifteen days before his 77th birthday, after being hospitalized in Tallinn for months.