Police are appealing for witnesses after arsonists set fire to a cabin at the boating lake in Tilgate Park, Crawley.
Firefighters were called at 4.20 this morning (Tuesday September 24) but the cabin was well alight when they arrived.
The cabin – Tilgate Activity Centre – was used by Dynamic Adventures.
Andy Whitelock , of Dynamic Adventures, said the equipment lost in the fire, including kayaks and dinghies, would cost more than £10,000 to replace.
A spokesman for Sussex Police said: “The fire is believed to have been deliberate and all the equipment inside has been destroyed.
“Officers are investigating and anyone with information is asked to contact police on 101 quoting serial 128 of 24/09.”