Eight people including five children were rescued from Beachy Head on Sunday night (September 7) after they were cut off by the rising tide.
A spokesman for Eastbourne RNLI said the group had planned their expedition and consulted tide tables but seriously underestimated the terrain and the type of footwear and clothing they would require.
The spokesman said: “Their intention was to walk along the beach from Birling Gap pass the Beachy Head lighthouse and on to Holywell.
“With some of the group wearing flip-flops their progress was extremely slow and with less than half of the route covered they found themselves cut off by the rising tide and darkness beginning to fall.
“Unable to use mobile phones to request assistance because of the lack of signal below the cliffs they realised their plight was desperate.
“With little alternative, they sought the highest ground possible and waited whilst one of the adults scrambled over the rocks and headed towards Holywell hoping to pick up a signal on his phone.
“Eventually he was successful and frantically dialled 999 and alerted Dover Coastguard.
“Initially it was understood that only three casualties were involved so Eastbourne RNLI’s inshore lifeboat was launched. Soon on scene, the volunteer lifeboat crew became aware of the extra casualties and requested the launch of Eastbourne’s all-weather lifeboat (ALB) to assist with the evacuation.
“The volunteer inshore lifeboat crew stayed on the beach to reassure the cold and frightened casualties to await the arrival of the ALB. When the ALB arrived on scene the casualties were ferried to the ALB by the inshore lifeboat where their medical condition was assessed.
“With all well the party were taken to Sovereign Harbour where they were met by local coastguards and police officers.