London Array offshore wind farm rescue operation
A practice rescue operation involving a ship crashing into an offshore windfarm is taking place in the Thames Estuary.
The drill at the London Array will involve 500 people with coastguards practising a scenario where a small cruise liner loses power.
When completed the London Array will be one of the world's largest offshore wind farms with 341 turbines.
The Maritime and Coastguard Agency said the exercise would test current resources and planning.