Organisers of the Newhaven West Beach picnic protest estimated up to 400 people took part in the demonstration on Saturday August 17.
Ladders were used to help protesters scale the wall and get on to the beach at around lunch time.
The demonstrators, many of whom came dressed as pirates, enjoyed a picnic on the beach until heavy rain set in at about 3.30pm.
Protest organiser Heather McClean said: “The turnout was really quite impressive.
“Thank you to everyone for coming.
“We are going to keep on fighting and we are not going anywhere.
“We are doing this for our kids and their kids.”
Heather said she had not seen the car park so full since the 1990s, when the beach was open to the public.
Residents has brought banners to the demonstration, with some reading: ‘Knickers to NPP.’
Even Newhaven mayor Julie Carr, district councillor Rod Main and Newhaven county and district councillor Carla Butler were spotted taking part in the demonstration.
One protester helped lift dozens of people up over the wall.
A children’s entertainer and musicians were on hand to entertain the crowds.
Heather added: “The protest was really nice and friendly. It was a lovely atmosphere.
“We want to make it clear that we want the beach as a community space.
“We do not want to impede the workings of the port in any way.”
Organisers We Love Newhaven and the Newhaven Village Green Preservation Society are planning to organise another Ladder Party soon.
They are also running an art project with the children, who are drawing pictures showing their experiences of the beach, leading to an exhibition of their work.
Newhaven Port and Properties closed the beach in 2008 due to health and safety concerns.
Since then Newhaven Town Council and Newhaven Port and Properties have been locked in a legal battle over access to the beach.
The town council was granted permission by the Royal Courts of Justice to turn the beach into a village green to guarantee access. However Newhaven Port and Properties is seeking permission to appeal to the Supreme Court against the decision.
Photos courtesy cllr Rod Main.