A group of divers used the 15-m long rented yacht Andromeda to damage the Nord Stream gas pipeline in September 2022. According to a reconstruction by the Hamburg weekly “Der Spiegel,” the Andromeda traveled from the German port of Rostock on September 6 to the German island of Ruegen, then on to the Danish island of Christians, which was close to the explosion location on September 26.

Questions surround the amount of explosive used for the sabotage, which likely weighed several hundred kilograms of material, as well as the need to haul all of the diving gear given the vessel’s modest size. This has caused some people to question if a second vessel will actually be involved in the operation.

The German weekly reported that one of the six crew members had a fake Bulgarian passport, but the authorities have not yet determined the nationality of the saboteurs or even established a connection to a particular government. The New York Times has claimed that a “pro-Ukraine gang” was responsible for the sabotage.

The party that chartered the Andromeda was made up of persons dressed as regular sailors, who were seen putting shopping bags full with supplies aboard the boat and speaking a language that “seemed to him Polish or Czech,” according to Der Spiegel, who quotes a Ruegen harbor master. There was a woman and several males in there.

A sailboat built by the German Bavaria Yachts, the Andromeda is a Bavaria C50. She has five cabins inside with enough for 11 passengers. At the stern, she has a deck from which divers can enter the water. According to Der Spiegel, the Baltic Sea is roughly 80 meters deep where the explosions occurred, necessitating professional diving abilities and specific air tanks, one filled with a helium-oxygen combination and the other with pure oxygen.

In the area of the sea in question, each dive would have forced the boat to stop for longer than three hours. Four dives spread over a few days would likely have been necessary to lay explosives on two pipelines that are 4 km apart.

But not everything in the reconstruction appears to be linear. Several of the specialists consulted note that such lengthy and deep dives would have required divers to use a decompression chamber, which would not fit on a yacht. There are also questions about whether there would have been enough room to transport the necessary quantity of explosives. According to the governments of Denmark and Sweden, the blasts had the force of “several hundred kilograms of explosive,” however some experts believe up to 2,000 kilograms would have been needed.

“We’ve been given a component of a puzzle. Yet we are unsure of its size. How many pieces does it have—50, 500, or 5,000?” Christian Moelling, director of the security and defense division of the German Council for International Relations’ Deutsche Gesellschaft fuer Auswärtige Politik, pondered. “Was a second boat present? And who is transporting the explosives on behalf of someone else? Because of this, I believe that now, some puzzle pieces are lacking.” The chairman of the Bundestag’s intelligence oversight committee, Konstantin von Notz, asked the press “to be as cautious as possible with any judgments at this time”.

It is very likely that the investigation “has to do with a state or quasi-state actor because it is very demanding to transport large quantities of explosives – we are now talking even two tons – without being noticed in the right place in the Baltic, transport them to a relevant depth in order to trigger more explosions in a controlled way,” he told Die Zeit. However, when a terrorist attack is supported by the government, it is more likely that incorrect or misleading information was intentionally spread.