Around May 14 through 17, 1792, American Captain and fur trader Robert Gray explores Grays Bay on the Columbia River shore of present-day Wahkiakum County, and charts the outlet of Grays River where it enters the Bay. Grays Bay is an embayment on the north bank about 20 miles upstream from the mouth of the Columbia River. The various branches of Grays River rise in the Willapa Hills on the boundary ridge between Lewis and Wahkiakum Counties in southwest Washington, draining 124 square miles before flowing into the Columbia at Grays Bay. Both are named for Robert Gray.

Although he charted them, Robert Gray did not give his name to either the bay or river that now bear it. British Royal Navy Lieut. William Broughton named Grays Bay for Gray in the fall of 1792, when he was sent by Captain George Vancouver, with a copy of the chart Gray had made, to further explore the Columbia.   Vancouver and Gray had met at the mouth of the Puget Sound, and exchanged charts and summaries of discoveries.

Gray and the crew of his ship, the Columbia Rediviva, became on May 11, 1792, the first whites to succeed in entering the river called by its Chinook inhabitants Wimahl ("Big River"). The Columbia sailed a few miles upstream and anchored off Qwatsamts, an old and important Chinook village consisting of three rows of large cedar plank longhouses. When the whites asked the name of the village, they heard something that sounded to them like "Chinook," and the village, the point on which it was located, the inhabitants, and ultimately all the people of the lower Columbia came to be known as Chinook.

The city of Chinook, WA, now occupies that site.

Gray and his crew spent several days there filling their water casks and trading with the many inhabitants for furs, especially the sea otter furs that the whites coveted.

Exploring Upriver

Around May 14, Gray weighed anchor and set out to explore farther up the river. The ship followed a narrow channel along the north bank, which became increasingly hazardous due to sand bars. By afternoon the Columbia had run aground briefly and floated off, and Gray sent a small boat ahead to scout the channel. The crew of the boat soon determined that the channel on the north was not navigable much farther, and that the main channel ran along the south shore of the Columbia.

However, Gray and his men had already noted that the Indians coming from upriver had no sea otter pelts. Since otter were the main goal of the expedition, they decided not to venture farther up the river. They anchored the Columbia near where they had run aground, in a large bay on the north bank of the river. The next day Gray went ashore to view the land, and according to some reports formally claimed possession for the United States. Gray made a chart of the area that showed Grays Bay and the mouth of Grays River.

Return to Sea

After refitting his ship for the sea, around May 17 Gray left the Bay and turned the Columbia back down the river he named for it. On May 20 he crossed the bar at the mouth of the Columbia into the open sea and headed north. After another summer trading around Vancouver Island, Gray sailed via Hawaii to China, where he sold or traded the furs he had acquired. From China he sailed around the Cape of Good Hope for home, reaching Boston in July 1793.

Eventually, the larger of the two rivers flowing into the Bay came to be known as Grays River -- it had also been known by the Indian names Ebokwol and Moolhool.