After leaving the present-day site of Sacajawea State Park, the explorers moved quickly down the Columbia River. When they first saw one of the Cascade volcanoes, it was proof they were approaching the ocean. As they proceeded downriver, the Corps of Discovery began to see other signs they were nearing their final destination. Some of the native people had pieces of brass and copper, beads, and red and blue cloth – all from European and American trading ships that stopped at the mouth of the Columbia to trade with the Chinook Indians.