The bottom where Estonia is located consists of 5–30 meters of soft clay, according to documents requested by the Swedish Accident Investigation Board. On the raw material from the films to the documentary "Estonia - the find that changes everything", it appears to be rock formations around the ship. But wreck expert Linus Andersson, who was present when the documentary was filmed, is convinced that it is in fact Baltic Sea clay.
The Accident Investigation Board Norway has received material that supports that view. A report from 1996 states that the bottom where Estonia is located consists of soft clay - between 5 and 30 meters thick. The clay is thickest on the south side where the ship is located and thinnest on the north. According to the report, there is harder moraine under the clay. About 100 meters from the north side of the ship there is a harder bedrock under the mud. The report was made by Delft Geotechics and commissioned by the Swedish Maritime Administration. It reviews the conclusions of several bottom surveys conducted during the years 1994-1996.
The investigations include a large number of boreholes in the area as well as other analyzes. Martin Schreuder, senior lecturer at Chalmers University and expert on ship stability, says that it is not reasonable and completely unlikely that the hole shown in the documentary "Estonia - the find that changes everything" could have occurred if the bottom consisted of 5-30 meters soft. Linus Andersson has examined several other wrecks near the place where Estonia is located. Even there, the bottom consists of clay, he says. My opinion is that there is no rock formation or rock where Estonia is located.