British ship Sir Galahad is carrying 650 tonnes of food, medicine and fresh water for the Iraqi people.
It was escorted into Umm Qasr by patrol ships, armed helicopters and inflatable boats with machine guns.
The ship should have arrived two days ago, but was delayed by poor weather and mines found in the water approaching the port.
The mines were detonated by special teams - some working with dolphins who carry small cameras on their fins.
Aid agencies are pleased the ship has arrived safely, but are worried how the aid will be handed out, as the people most in need live in areas still controlled by Iraqi forces.
The most immediate problem is in Basra, which has been without proper water supplies since last Friday.
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