Volunteers from Newhaven Lifeboat conducted a search for almost six hours after a boy was washed into the sea during a severe storm.
The 14-year-old boy was pulled into the waves west of the main breakwater at around 4.20pm on Sunday October 27 while swimming with friends.
The lifeboat was assisted by local Coastguard teams on the beaches and Coastguard helicopter Rescue 104.
Lifeboat crew battled large waves and a huge backwash from the West Arm in what were extremely tough conditions.
Despite a long and comprehensive search, the teenager has not been found.
Newhaven Lifeboat press officer Alan Novis said: “Our crew battled some very challenging conditions, doing everything possible with our Coastguard colleagues on the beaches and in the air to try locate the missing boy.
“One crew member suffered bruising during the search and the lifeboat sustained some slight damage by the exceptionally large waves.
“This is a very distressing incident; our thoughts are with the family at this incredibly difficult time.”
A decision will be made this morning by Coastguards as to whether the search will be resumed.
The friends were not swept off and are safe.
Sussex Police said all agencies are reminding people of the dangers of being at seashores in bad weather.
The advice is straightforward - stay clear.
Chief Inspector Katy Woolford added; “Both we and the Coastguard have received reports during the afternoon of people being dangerously near water edge in places as far apart as Seaford and Brighton.
“Please, at least until the imminent severe weather abates, stay clear of the seashore for your own safety, and in order to help the emergency services to be available to deal with other incidents.”