They further cited a named lieutenant commander of the Danish navy and analyst at the Royal Danish Defence College for several reasons why it is not credible that such a small vessel was used for the sabotage. The force of the explosion and the widely dispersed debris implies that several hundreds of kilograms of explosives were used, an amount that is impractical to transport with such a small sailboat. Secondly, it is surprising that traces of explosives were found on the yacht, since in this case clearly no homemade explosive device was used. Thirdly, accurately placing the explosives on the bottom above the pipeline at 60–80 meters depth from a small surface vessel is practically impossible. The skepticism was shared by a named former chief analyst of the Danish Defence Intelligence Service now senior analyst in the Danish think tank Europa. The naval officer instead speculated that a submarine was used to place the explosives and pointed out that a sonar-equipped submarine can, with relative ease, accurately place a naval bottom mine with 500 kg of explosives.

https://en.wikipedia.org/wiki/2022_Nord_Stream_pipeline_sabotage#Involvement_by_Ukraine