Australia's capacity to respond to marine oil spills will be tested as part of an international conference in far north Queensland this week.

More than 500 delegates from shipping and environmental groups are attending Spillcon in Cairns to discuss prevention and response measures.

Australian Maritime Safety Authority spokesman Toby Stone says part of Trinity Inlet will be closed on Thursday for a demonstration on the water.

"It will include a demonstration of the use of hazardous response scenarios," he said.

"There'll be a helicopter there, simulated application of dispersants, this is to spray the oil on the water from two aircraft.

"I might add that we're not using real dispersant - it will of course be water."

He says there will be the latest deployment of boom and containment equipment recently purchased for areas such as Townsville.

"We've got nine strategic stockpiles around Australia," he said.

"We work very closely with industry - we are in pretty good shape.

"We've just had a rewrite of the national plan, which is in draft at the moment.

"That's a national plan for maritime environmental emergencies."