POLICE are investigating whether alcohol or speed contributed to the early morning crash of a speedboat on Victoria's Lake Eildon that left an 18-year-old woman dead.

Casey Hardman was thrown into the water after the 5.5m speedboat, being driven by a 16-year-old boy, collided with a dead tree in an inlet at the popular lake resort in central Victoria about 1.30am yesterday.

Police said the teenage driver unsuccessfully attempted to find Ms Hardman in the water before driving the speedboat to a nearby houseboat to raise the alarm.

Ms Hardman's body was recovered by people from the houseboat a short time later, but she could not be revived.

Police said she appeared to have suffered severe head and chest injuries in the collision.

Ms Hardman, from the outer northeastern Melbourne suburb of North Ringwood, was holidaying at Lake Eildon with her brother and friends.

The 16-year-old, who suffered minor injuries in the collision, was believed to be a licensed boat driver. He was not related to the Hardman family.

Ms Hardman's father, Mark, yesterday described his daughter as "my brightest spark".

"She's a very outgoing young girl, very friendly," Mr Hardman said. "She was the life of the party and I know that she's going to be truly missed by many of us."

Police are investigating whether life jackets on board the boat were used, if the boat had the correct lights and if alcohol had been consumed.

"The tree was 60m out from the shore and hard to see without good lights, there was no moon (and) it was pitch black," Senior Constable Brett Tanian said.