The incident happened late Monday night as the 228-metre Amakusa Island was about 15 kilometres from Ridley Island, the coal loading facility south of Prince Rupert.
The port authority says the big ship was shifting its position from berth at the coal terminal to its assigned anchorage when it grounded in the outer harbour and visibly listed.
A team of coast guard and other experts assessed the situation and the rising tide helped refloat the bulk carrier about four hours later.
The Amakusa was able to make it to anchorage under its own power and doesn't appear to have caused any environmental damage.
A release from the port authority says it continues to monitor the situation.