Viking ships were treated with tar, produced from resinous pine trees. About 600 litres were needed to treat a longship. The film shows present-day tar burning in Finland. The pyre contains 60 m3 of cleaved and carefully stacked pine roots. It burns for four days and about 2,000 litres of tar are produced. In the past, roots were dug up by hand, and in total, somewhere between 3,000 and 4,000 man-hours were probably required to produce 1,000 litres of tar.