The scouts fundraised to purchase the stolen items a couple of years ago, worth approximately $3500 said Body.
Local residents alerted the group about the burglary on Saturday morning after discovering the gates, which are locked by the council every night, had been cut open.
The metal cladding and wood framing of one of the shed walls was also cut through, through which the building was entered.
Body said the group spent "thousands" reinforcing the doors of the shed in 2015, after they were vandalised by people trying to enter.
"Then these s***s came through the wall.
"There is great cost involved in reinstating the damage to the shed, to a standard that prevents other people from breaking in."
The group does not have insurance, so replacing the stolen items will take months of fundraising, said Body.
Lost for words this morning :( Sometime during last nights storm some low-lifes broke the bolt on the gates into...
Posted by Riverhead Scout Group on Friday, 26 August 2016
"It means we can't do water activities this summer as a group because we don't have enough kayaks left for everyone to use."
The committee will next meet on September 12, when they will discuss plans to replace the stolen items.
A police spokeswoman said they were investigating.
Items stolen:
• 1 orange kayak marked S1
• 1 orange/yellow/red kayak marked S9
• 1 yellow/orange kayak marked S10
• 1 yellow kayak marked S11
• 6 plastic oars
• 2 red life jackets
• 4-6 kayak seats