The search for a man who disappeared under the water in a Rotorua lake has now entered its third hour.

Emergency services including police, Coastguard and the Rotorua Harbourmaster have been searching for the 48-year-old since he was first reported missing shortly after 2pm.

Speaking to Fairfax, a police spokesperson says the man's lifejacket is believed to have come off after he jumped off a boat into the lake. At the time of the incident other people were on board the boat which is understood to have launched from Te Karaka Bay.

Police were searching about 635m from shore, between Te Rerengaotemokai​ Point and Matawhao Point. A helicopter also spent 90 minutes searching but was called off the job before 5pm.

Four boats remain out on Lake Rotoiti scouring the waters for the man.

The police dive squad has been called and will be used on Thursday morning if the man is not found tonight.

-stuff.co.nz