A vegetation fire on Sulphur Point is the latest in a spate of blazes across Rotorua being treated as suspicious.
Fire crews were called out to the 20m-long blaze on Sunday around 3.30pm.
Firefighters were at the scene for an hour and 20 minutes containing the blaze and ensuring it would not spark back up.
Earlier this month firefighters were called to a small vegetation fire in the reserve near Pohutukawa Ave, as well as a fire in Linton Park that took five fire trucks and 30 firefighters to extinguish.
In November a large blaze in Sulphur Bay, spanning about a kilometre, was battled by 10 fire appliances and two helicopters with monsoon buckets.