Hundreds of people heading to the Isle of Wight Festival were held on boats in the Solent because of traffic gridlock on the island, forcing ferry companies to suspend services.
Mud, caused by heavy rain, led to most of the problems.
Earlier about 600 people had been forced to sleep in their cars overnight following the traffic problems.
ITV reporter Tom Barton reports:
The problems started after heavy rain fell yesterday, water-logging the event car parks at Seaclose Park, Newport, meaning that they became churned up with mud as cars began to arrive.
This led to the car parks becoming inaccessible and long queues forming, stretching back to the port towns of Ryde and Cowes.
Police led many of those waiting to Newport Football Club where they were given shelter overnight.
Now organisers are urging anyone still waiting to get to the island to leave their cars.
While some ferry services have now returned to normal, Hampshire Police said in a statement that they still expect "significant delays" for Isle of Wight Festival revellers today.