The Canadian Coast Guard says a barge has sunk in the Graham Reach.
It happened just after 7 p.m. Sunday near Klemtu.
A tug owned by a company in the U.S. confirmed to the Coast Guard the barge was carrying sand and gravel.
Officials say there was no pollution or recoverable product.
No one was on board the barge when it flipped and sank. The crew on the tug are safe.
The crew was given permission from Transport Canada to continue its journey to Alaska.
Officials remain on scene to assess the situation.
Choppy waters and high winds were reported at the time of the incident.
This is the second accident in just over three weeks.
Last month, a tug and barge went aground in the Seaforth Channel just west of Bella Bella.
The barge was recovered and has since been taken away from the scene, but the tug sank and leaked thousands of litres of diesel.