Afterward, Gray carried on south to what was, he rightly suspected, the mouth of a great river, and looked further for a way into this river. On May 11, his men discovered what he sought, and he ordered a small sailboat launched to attempt to find a safe passage across the sand bars in the process known as sounding. Finally, on the evening of May 11, 1792, Gray's men found a safe channel, so ship and crew sailed into the estuary of the Columbia River. Once there, they sailed upriver and Gray named this large river Columbia after his ship.