Swedish-born mariner Peter Hedland was the first European to note the harbour's existence and the possibility of using it as a port. Peter Hedland arrived in the area in April 1863 on board his boat "Mystery", which he had built himself at Point Walter on the banks of the Swan River. He named the harbour Mangrove Harbour and reported that it would make a good landing site with a well protected harbour, and that there was also fresh water available. However, the port was initially regarded as unusable, due to a sandbar that frequently sealed the entrance and thick mangroves round the shore; further, the narrow entrance made the harbour difficult to enter in bad weather.