Water Police are investigating a boat collision on the Finniss River this morning.

Territory Duty Superintendent Rob Burgoyne said a 5m vessel skippered by a 28-year-old man allegedly crashed into a 3.5m dinghy with family of four on board about 11.30am.

“In the dinghy, an adult male was uninjured, but a 27-year-old woman and their two children aged six and two were flown to Royal Darwin Hospital by Careflight. The 27-year-old woman remains in a critical condition," he said.

“The driver of the larger vessel was uninjured.”

Alcohol was not a factor.

Anyone who witnessed the crash should contact police on 131 444.