A 20-year-old Victorian woman has been killed in a jet ski accident in Thailand.

Kyabram woman Emily Jayne Collie was holidaying in Phuket when her rented jet ski collided with another jet ski being ridden by her boyfriend, Tommy Keating.

Ms Collie suffered serious neck and shoulder injuries in the accident, which occurred at about 4:45pm (local time).

She was brought ashore at Kata Beach, where lifeguards performed CPR, but they were unable to revive her.

Ms Collie was pronounced dead before arrival at a local hospital.

Her boyfriend sustained only minor injuries.

Mr Keating reportedly told the sea rescue centre of Karon Municipality that the strong reflection of the sun on the water caused the accident, according to local media reports.

Emily Jayne Collie pictured alongside her boyfriend Tommy Keating. ( Facebook )

But Thai police told the ABC they were still trying to establish why the jet skis crashed.

"It is difficult to do the questioning as [Mr Keating] is very upset and he has been crying all the time, we can't communicate with him properly," said Police Major Patiwat Yodkwan, Inspector of Karon police station.

"Police have been coordinating with Australian Embassy representative.

"We were informed that relatives from both sides are on the way to Thailand [and] hopefully he will be more calm after being with family."

Tributes have flowed for Ms Collie, who was a third year pharmacy student at Charles Sturt University.

"Fly high gorgeous... we will all miss your amazing laugh and bubbly personality," said friend Brodie Tyacke.