Authorities are continuing to monitor the environmental impact of a yacht that sank near the Great Barrier Reef off far north Queensland last week.

The $15 million Seafaris caught fire with 16 people on board on Thursday off Cow Bay, north of Cairns, and is now sitting on the sea bed.

Maritime Safety Queensland general manager Patrick Quirk says divers have detected a few small bubbles of diesel escaping from the wreck.

But he says they have not been plugged because of the risk of further damage to the hull.

"In the meantime, we're doing regular patrols of the beaches around Cow Bay and yesterday we picked up four ute-loads of rubbish which was deposited to the local tip," he said.

"We're conscious that we don't want to leave any residue at all in the Great Barrier Reef area."