Brother Jonathan was a paddle steamer that struck an uncharted rock near Point St. George, off the coast of Crescent City, California, on July 30, 1865. The ship was carrying 244 passengers and crew, with a large shipment of gold. Only 19 people survived, making it the deadliest shipwreck up to that time on the Pacific Coast of the United States. Based on the passenger and crew list, 225 people are believed to have died. Its location was not discovered until 1993 and a portion of the gold was recovered in 1996. The ship was also instrumental in setting off the 1862 Pacific Northwest smallpox epidemic, which killed thousands of Indigenous people in the region.

A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S.S. or S/S (for 'Screw Steamer') or PS (for 'Paddle Steamer'); however, these designations are most often used for steamships.

The term steamboat is used to refer to smaller, insular, steam-powered boats working on lakes and rivers, particularly riverboats. As using steam became more reliable, steam power became applied to larger, ocean-going vessels.