Colman Dock, also called Pier 52, is the primary ferry terminal in Seattle, Washington, United States. The original pier is no longer in existence, but the terminal, now used by the Washington State Ferries system, is still called "Colman Dock". The terminal serves two routes to Bainbridge Island and Bremerton and has an adjacent passenger-only facility at Pier 50 for King County Water Taxi and Kitsap Fast Ferries routes.

Originally Colman Dock was located at the foot of Columbia Street, and was immediately to the north of Pier 2. Before 1910, the wharf immediately to the north of Colman dock was used by the West Seattle ferry. In 1910 this wharf was replaced with the Grand Trunk Pacific dock. In 1964 the entire area was used for the much larger ferry terminal dock which exists today.

Pier 52 was historically known as Colman Wharf. The original Colman Dock was built by Scottish engineer James Colman in 1882 for the Oregon Improvement Company's coal bunkers. It burned with most of the rest of the city in the Great Seattle Fire of 1889, but was quickly rebuilt. In 1908, Colman extended the dock to a total length of 705 feet (215 m) and added a domed waiting room and a 72-foot (22 m) clocktower. This expansion was designed by the Seattle architectural firm Beezer Brothers.

Colman also set up a company, the Colman Dock Company, to conduct the dock's business affairs. Following the merger of the La Conner Transportation Company, headed by Joshua Green (1869–1975), with the Puget Sound Navigation Company (PSN), headed by Charles E. Peabody (1857–1926) the Colman Dock Company, and the Colman Dock itself, came under PSN control. In 1910, PSN was approaching monopoly control over the inland steamship routes of western Washington, with the company's most serious challenger being the Kitsap County Transportation Company (KCTC), headed by Kitsap County businessman Warren L. Gazzam (1864–1961). The rivalry between the two companies became almost a personal matter between Green and Gazzam. In 1910, Green, having obtained control of Colman Dock, and engaged in a rate war with KCTC, ordered KCTC not to land its boats at Colman Dock. KCTC then moved several piers north, to the Galbraith, Bacon dock.

Colman Dock was seriously damaged when, on the night of April 25, 1912, the steel-hulled ship Alameda accidentally set its engines "full speed ahead" instead of reversing, and slammed into the dock. The dock tower fell into the bay and the sternwheeler Telegraph was sunk. The clock was salvaged, as was the Telegraph, and the dock was reconstructed with a new tower. No one died in the Alameda accident, but a less dramatic accident the following month proved fatal. On May 19, 1912, a gangplank collapsed as passengers were boarding the Black Ball steamer Flyer. At least 60 people fell into the water. One woman and one child died.

In 1917, Colman Dock was owned and operated by Colman Dock Company, with B. P. Morgan as manager. Colman Dock was the terminal of the Puget Sound Navigation Company, the Merchants Transportation Company, and several Puget Sound shipping lines. Colman Dock measured 700 by 115 feet (213 by 35 m), with 1,400 feet (430 m) of berthing space. In 1917 an overhead walk (still in existence in 1983) led from the Seattle business district to the waiting room, from which most of the Puget Sound steamship passenger traffic originated. There were also adjustable passenger gangplanks and adjustable freight slips. In 1917 Colman Dock was equipped with a Barlow marine elevator. Colman Dock could accommodate 14 Puget Sound steamboats at one time. There were offices on the north side of the overhead walk.

In the mid-1930s Puget Sound Navigation Company modernized Colman Dock, using an Art Deco style that matched their streamlined signature ferry MV Kalakala.

In 1935, Colman Dock became the Seattle terminal for what had been the Alki–Manchester ferry when the dock at Alki Point washed out.