Luxury houseboat Ocean moored on the river Thames, near Albert Bridge, London
Foxtons believes the three-bedroomed vessel, which even has its own swimming pool, is the most expensive houseboat it has marketed.
The boat is 1,388 square foot and boasts three en-suite bedrooms - including one with a dressing room - a kitchen and dining area, a reception room, a study and a utility room, as well as a 577 square foot deck.
The boat, Ocean, is finished to a high specification throughout, with a modern open plan kitchen and a roll top bath in one of the bathrooms.
But the main attraction is its mooring at Cadogan Pier, by the Albert Bridge in Chelsea, a few minutes' walk from the King's Road.
Foxtons said although the price tag was high, it was good value compared with properties in the area.
It said the price worked out at around £720 per square foot, excluding the swimming pool and the terrace, compared with a cost of around £1,000 per square foot for flats in the same location.
Ian Brownridge, sales manager at Foxtons' Sloane Square office, said: ''We have had quite a lot of interest in it.
''People love it but they find it difficult to get their head around spending £1 million on a boat.''
Ocean's present owners bought the boat in France and sailed her back to the UK. But Mr Brownridge said that after several years aboard her, they were ready for life on dry land again.
The houseboat has a 577 square foot deck
The 1,388 square foot boat boasts three en-suite bedrooms, including one with a dressing room