Police, coastguard and RNLI crews were scambled at about 4.15pm yesterday after the incident at West Beach, Nehwaven.
After a six hour search, crews were stood down at about 10.30pm last night with the plan to resume this morning. A spokesman for the Marine and Coastguard Agency said the search has been stopped pending new information.
However the Newhaven in-shore lifeboat is carrying out a further search of the shoreline and a police helicopter has been checking the shoreline for several miles each side of Newhaven. Local police officers have also been searching along the beach and helping reassure the local community.
Chief Inspector Katy Woolford of Sussex Police said: "All agencies are continuing to do everything possible to find the boy, and our thoughts are very much with the family at this time." Friends of Dylan, who is believed to be a pupil at Tideway School in Southdown Road in Newhaven, have set up tribute pages on Facebook for friends, family and strangers to leave comments.
One user on the social networking site, who claims to be a friend of Dylan's, has posted a picture of a young boy standing inches from rough waves. Coastguards said they would not restart the search for Dylan unless they received new information from police.