The Building of the Boat was a projected Wagnerian opera for soloists, choir, and orchestra that occupied the Finnish composer Jean Sibelius from 8 July 1893 to late-August 1894, at which point he abandoned the project. The piece was to have been a collaboration with the Finnish author J. H. Erkko, whose libretto adapted Runos VIII and XVI of the Kalevala, Finland's national epic. In the story, the wizard Väinämöinen tries to seduce the moon goddess Kuutar by building a boat with magic; his incantation is missing three words, and he journeys to the underworld of Tuonela to obtain them. In July 1894, Sibelius attended Wagner festivals in Bayreuth and Munich. His enthusiasm for his own opera project waned as his attitude towards the German master turned ambivalent and, then, decisively hostile. Instead, Sibelius began to identify as a "tone painter" in the Lisztian mold.

Jean Sibelius was a Finnish composer of the late Romantic and early-modern periods. He is widely regarded as his country's greatest composer, and his music is often credited with having helped Finland develop a stronger national identity when his country was struggling from several attempts at Russification in the late 19th century.