SS Pacific was a wooden sidewheel steamer built in 1850 most notable for its sinking in 1875 as a result of a collision southwest of Cape Flattery, Washington. Pacific had an estimated 275 passengers and crew aboard when she sank. Only two survived. Among the casualties were several notable figures, including the vessel's captain at the time of the disaster, Jefferson Davis Howell (1841–1875), the brother-in-law of former Confederate President Jefferson Davis. The sinking of Pacific killed more people than any other marine disaster on the West Coast at the time.

Design and construction Pacific was commissioned by Major Albert Lowry, Captain Nathanial Jarvis, and her builder, William H. Brown. She was built in Brown's shipyard at the foot of Twelfth Street on the East River in New York. Her hull was oak and live oak timbers fastened together with iron and copper nails. Pacific had a vertical beam steam engine generating . Her engine had a cylinder with a stroke. She had two coal-fired boilers. Her machinery was manufactured by the Archimedes Iron Works run by H. R. Dunham of New York.

Pacific sailed with as many as 546 passengers aboard in two classes of service. Passengers purchasing individual cabins would dine in the ship's salon, while steerage passengers had berths in common areas and ate in a separate mess.

She was launched at high water on September 24, 1850. The next day she had a gala sea trial. Captain Jarvis was in command. Also aboard were William Brown, her builder, H. R. Dunham, who supplied her machinery, General Jose Antonio Paez, exiled President of Venezuela, several other steamship captains, and other invited guests. As Pacific headed down the East River, the new steamship Franklin and the new Cunard steamer Asia raced the ship. She easily passed both ships hitting a speed of just over . A cold lunch was served underway. The ship arrived back at her berth in the East River a 5:45 P.M. after an trip.

Panama service (1850–1851) Pacific sailed from New York on her first commercial voyage on October 11, 1850. She had 80 passengers aboard. She was bound for Havana and finally New Orleans, where she arrived on October 23, 1850. She took up a regular route shuttling between New Orleans, Havana, and Chagres, Panama for the Pacific Mail Steamship Company. Her schedule connected her with the company's ships sailing to San Francisco (via Panama) and New York (via Havana).

The California gold rush was in full swing at the time, and the quickest way to and from the goldfields was through Panama. Thus, Pacific had its share of dramatic cargoes. She left Chagres with 470 passengers and about $200,000 in gold dust on December 12, 1850, bound for Havana and New Orleans. Her previous trip had been even richer. She left Chagres on November 11, 1850, with $287,000 of California gold dust and 353 passengers including Prince Paul of Württemberg.

In 1850, there were no overland communications routes across North America, so news and mail from California reached the eastern United States through the steamship links at Panama. The news of Western United States brought to New Orleans by Pacific was frequently the first word of events to reach the wider world. The news was telegraphed across the country from New Orleans. While this might have been the fastest method of receiving California news, it was a slow process. For example, the most up to date newspapers that reached New Orleans aboard Pacific on February 6, 1851, were dated January 1, 1851.

Nicaragua service (1851–1855) Cornelius Vanderbilt made his fortune in regional steam boating in the New York area. When the California gold rush made shipping through Panama profitable, he saw an opportunity for improvement. He believed that a route across Nicaragua, which was closer to the United States, would prove a quicker and cheaper path to the gold fields of California. He was unable to secure financing for a canal as he had hoped, but used instead a route including the San Juan River and Lake Nicaragua. The transit time from New York to San Francisco on the new Nicaragua route was variously reported to be two to five days faster than the Panama route. Vanderbilt began buying and chartering ocean-going ships in both the Atlantic and Pacific to make the Nicaragua route a reality. He chartered Pacific from Brown for the Nicaragua to San Francisco section. She sailed under Captain David G. Bailey.

Pacific left New York on March 18, 1851, to take up her new charter. She sailed to San Francisco with a stop in Valparaíso, Chile. Pacific departed San Francisco on her first voyage as part of the new Nicaragua route on July 14, 1851. She stopped for coal in Acapulco on July 23, and reached San Juan del Sur, the Pacific end of the Nicaragua route, on July 27, 1851. Her arrival in Nicaragua was coordinated with the sailing of Vanderbilt's Prometheus, which left New York for Nicaragua, also on July 14, 1851. This inaugural run of Vanderbilt's new route did not go as planned. A $40 or $50 "transit charge" levied in Nicaragua was twice what passengers had been promised, and the mule trains which carried baggage between the steamships were likewise more expensive than advertised. Worst of all, they spent three weeks, "among the vermin, filth, and disease of Nicaragua." The outraged passengers went so far as to form a committee to publish a scathing review of the new service, although they commented favorably on Pacifics Captain Bailey.

Captain Bailey died unexpectedly while Pacific was in port at San Juan del Sur during the fall of 1851. Captain Jarvis was restored to command of the ship, at least through February 1852.

The transit problems in Nicaragua were reduced and Pacific continued her shuttles between San Francisco and San Juan del Sur for several years. In 1853, through rates leaving San Francisco on Pacific, crossing Nicaragua, and sailing to New York on another Vanderbilt steamer were: $225 for deck staterooms, $200 for staterooms opening onto the dining salon, $150 for a cabin on the lower deck, and $75 for steerage. Her cargoes were even richer than on her Panama trips. In September 1853, she left San Francisco with 460 passengers and $1.5 million in gold.

The government of Nicaragua was not strong, which may explain how Vanderbilt got his license to cross the country in the first place. By 1854, this weakness brought about threatening forces. A town near the western terminus of the Nicaragua crossing tried to collect "port fees" and impose other controls on Vanderbilt's operations which were not called for in his charter from the national government. When these demands were rebuffed, armed men from San Juan del Norte seized one of Vanderbilt's employees. The U.S. Consul attempted to negotiate the matter and was wounded in the face when a broken bottle was thrown at him. Matters escalated and the bombarded the defenseless town for an hour and thirty-five minutes, destroying it.

While the outcome at San Juan del Norte favored Vanderbilt's interests, the civil war that broke out in Nicaragua in 1854 did not. The national government recruited American mercenary William Walker to defend it from the rebels. He and his band of 30 mercenaries took control of the country. He seized Vanderbilt's assets in Nicaragua in March 1855, likely in collusion with Vanderbilt's erstwhile partner, Charles Morgan. Pacific continued to sail into this confusing situation until at least August 1855.

Pacific Northwest service (1858–1869)

Pacific was "withdrawn" from the Nicaraguan service in early 1856. She falls out of contemporary accounts at that point. It may be that her charter was not renewed in the confusion that overtook Vanderbilt's operations after the seizure of his Nicaraguan properties. In the fall of 1858, she reappears sailing for the Pacific Mail Steamship Company between San Francisco, Portland, Puget Sound, and Victoria, British Columbia. Part of her business, and perhaps the reason for her reactivation was to ferry miners from California to the Fraser Canyon Gold Rush. She also carried troops amid escalating border tensions in the San Juan Islands with British forces. In January 1858, she embarked 260 enlisted men and 13 officers in San Francisco for Fort Vancouver on the Columbia River.

In 1859, Pacific was purchased by the California Steam Navigation Company which continued to sail her between San Francisco, Portland, Puget Sound, and Victoria. Much of her freight was agricultural. For example, she sailed from Portland to Victoria on November 15, 1861, with, "2,889 sacks flour; 991 boxes apples; 74 lbs butter; 19 boxes eggs; 28 sacks bacon; 3 barrels cider; 9 coops chickens".

Pacific, under the command of Captain George W. Staples, sailed from Portland down the Columbia on July 17, 1861, headed for San Francisco. At 2 A.M. she hit Coffin Rock. At the time she was making through the water and had a current with her. The rock stove in her bow and flooding was immediate and serious. Captain Staples attempted to reach Astoria, but the flooding was too severe. Pacific continued downstream for about and was beached on the Washington side of the river. When she came to rest, her stern was submerged to her second deck. There were 70 passengers aboard at the time. There were no deaths, but much of the cargo was destroyed. Pacific was refloated on August 2, 1861, and beached at Astoria for repairs. By the end of the year she was back in service, plying her regular route.

Steamboat rate wars raged on the West Coast of the United States in the 1860s. In order to reduce competition on the routes from San Francisco to points north, the California, Oregon, and Mexico Steamship Company acquired six ships, including Pacific, from the California Steam Navigation Company, in mid-1867. The California, Oregon and Mexico Steamship Company was reincorporated in California as the North Pacific Transportation Company in early 1869.

In 1868, a year after Alaska was acquired from Russia, Pacific was chartered for General Henry Halleck's inspection trip of the newly acquired territory. In addition to Halleck and his staff, the ship carried ordinance, commissary, and quartermaster's stores for the new military facilities. The ship departed San Francisco on July 29, 1868. The ship stopped at Fort Tongass, Sitka, and Victoria, B.C., before returning to San Francisco.

Southern California service (1869–1874) Beginning in 1869, Pacific began to mix her northward sailings to Victoria with southern voyages from San Francisco to San Diego with stops in Santa Barbara, and San Pedro. During the winter of 1869–1870, she took a two-month tourist cruise from San Francisco south to ports in the Gulf of California and then to Honolulu before returning.

In another attempt to damp down rate wars on the West Coast, the Pacific Mail Steamship company bought four steamships, including Pacific and all the Southern California business of the North Pacific Transportation Company in 1872. Pacifics sale price was $50,000. In August 1873 the ship underwent a refit in San Francisco. A new steam engine was installed which had a vertical cylinder with a throw. This new engine provided . In yet another corporate merger aimed at reducing competition, Goodall, Nelson, and Perkins purchased the Southern California operations of the Pacific Mail Steamship Company, including Pacific in early 1875. The ship sold for $35,000. Through all this corporate turmoil, Pacific continued her regular sailings. On March 11, 1873, she arrived in San Francisco with 90,000 oranges and 25,000 lemons from groves around Los Angeles. In 1874 she was making two round-trips per month between San Francisco and San Pedro.

Pacific Northwest service (1875)