Police Scotland is currently working with partner agencies to trace 15-year-old Liam Buchan from Dundee who was reported missing on Saturday.
He was with family and friends in the area of the river near Edzell around 4.45pm when when got into difficulty in the water.
Emergency services were contacted and a multi-agency response from Police Scotland, the Scottish Fire and Rescue, the Scottish Ambulance Service and HM Coastguard was launched.
Despite extensive efforts, the rescue was unsuccessful due to the challenging conditions and Liam remains missing.
Inspector Grant McGaughay said: “Search activity continued into Saturday evening, throughout the day on Sunday.
“Police Scotland’s Mountain Rescue Team and the Tayside Mountain Rescue Teams continue to search the River Esk today, while specialist officers from Police Scotland Dive and Marine Unit are also assisting in the search for Liam.
“Officers are also supporting Liam’s family at this difficult time and keeping them updated as our search continues.”
He added: “Liam’s family and would like to thank all agencies involved in the search and the local community in Edzell for the support they have shown so far.
“They would also like to warn persons not suitably trained or equipped not put themselves in danger in the search for Liam.”