Movie star and political activist Sean Penn, 45, was in the collapsing city to aid stranded victims of flooding sparked by Hurricane Katrina, but the small boat he was piloting sprang a leak.
The outspoken actor had planned to rescue children waylaid by the deadly waters, but apparently forgot to plug a hole in the bottom of the vessel, which began taking water within seconds of its launch.
When the boat's motor failed to start, those aboard were forced to paddle themselves down the flooded New Orleans street.
Asked what he had hoped to achieve in the waterlogged city, the actor replied: "Whatever I can do to help."
But with the boat loaded with members of the Oscar-winner's entourage, including his personal photographer, one bystander taunted: "How are you going to get any people in that thing?"