It was built over a three-year period by Peter Madsen and a group of volunteers, and cost approximately US$200,000 to build (1.5 million DKK).

[2] On 11 August 2017, Nautilus sank in the bay of Køge, in what investigators determined was a deliberate act by Madsen.

[3][4] The following day, Danish police had the submarine salvaged and brought onto land as part of the investigation of the death of Swedish journalist Kim Wall, who was last seen alive on board.

By August 2008, Nautilus could sail on its own, as the main diesel engine drive train and steering was completed.

The other drove a three-phase electric generator providing power for the onboard air compressor and battery charger.

There were more than a tonne of large 12-volt batteries on board, supplying the DC electric motor which could be operated alone or in tandem with the main engine on a chain-coupled drive for turning the 80 kilogram, five-bladed brass propeller.

[8] One such expedition was the attempted launch of the rocket and spacecraft HEAT 1X Tycho Brahe, built by Madsen's non-profit organization Copenhagen Suborbitals.

[11] On 10 August 2017, Nautilus was scheduled to sail from Copenhagen to appear in the afternoon at an exhibit on Bornholm, but Madsen sent a text notifying the crew that the trip had been cancelled.

Danish police visited a crew member to establish who was on board, and a large search operation was launched using helicopters and ships in the port of Øresund, just outside the harbour of Copenhagen.

[15][18][19][20] The following day, Danish police had the submarine salvaged, brought onto land and began processing it for evidence.