Aerial footage shows the barge docked off the Dorset coast that is being leased to house around 500 asylum seekers.
The Home Office confirmed the plan to house migrants for at least 18 months despite legal threats made by local Tories.
“Basic and functional accommodation” will be provided on the three-storey Bibby Stockholm along with 24/7 security.
Tory-run Dorset Council and local Conservative MP Richard Drax are considering launching legal action to prevent the barge being docked near the seaside resort of Weymouth.
Human rights organisations criticised the “cruelty” of “confining” hundreds of vulnerable people on a barge.
