Lorries are still used to carry the slate waste down to the port
A slate company is looking at beating rising fuel costs by switching some of its loads to sea transport.
Welsh Slate, which is based in Bethesda, Gwynedd, sells a million tonnes of stone aggregate a year.
Usually their crushed slate products travel by road but the company is increasingly using Penrhyn Port five miles (8km) away in Bangor.
Managing director Alan Smith said moving goods by sea meant cheaper costs and was better for the environment.
Using Penrhyn Port in Bangor also opens up the market, with products from Wales making their way by sea to the gardens of the Netherlands, said Mr Smith.
Closer to home the company sells crushed slate waste to the building trade and has started moving it by boat to the north west of England, he said.
"We are increasingly looking at the economics of moving aggregates as well as the environmental costs of moving products," said Mr Smith.
Penrhyn port was also a natural choice for the company as it was the hub of the local slate industry when it was at its busiest around a hundred years ago, he said.
Dafydd Roberts, the keeper at the National Slate Museum in Llanberis, welcomed the move to reuse the port for its original purpose.
"There is massive potential here," he said.
"This is a welcome development as slate waste is a heavy and bulky material with relatively low profit margins.
"So if it's possible to send it out to its customers in ways which don't impact on the environment and the cost is reduced then shipping is the answer," he added.