Masan is district of Changwon, a city in the South Gyeongsang Province, South Korea. Until 2010, Masan was an independent city and the capital of the province; it was merged with the neighboring Changwon. It lies along the Masan Bay (, Masan-man), approximately 35 km west from Busan.
Prior to the adoption of its current name, Masan was known as Happo (). Therefore, the old and still frequently used name for Masan-man is Happo-man.
August 1281 - After Korean officials encouraged Kublai Khan - head of the Mongol Yuan Dynasty - in 1265 that Japan would be easily subdued, the Koryo Korean state built over 300 large ships to aid an invasion of Japan. With over 20,000 Mongol troops as well as 5,000 Korean, the allied armies departed Masan on board 900 ships on August 15 of 1281 in an attempt to conquer Japan that eventually failed.
May 1, 1899 - The port of Masan was opened with pressure from Japan. Among the initial trading goods were salt, fish, cotton and other goods.
March 15, 1960 - A protest against electoral corruption was spearheaded by the Democratic Party in Masan. Approximately 1000 residents attended the demonstration, which took place at 19:30 in front of the Democratic Party Headquarters in Masan. The protest sparked violent clashes between demonstrators and police officers in which several students were killed. To restore order, authorities blacked out Masan and General Carter B. Magruder eventually dispatched US Marines to quell the unrest.
April 12, 1960 - The body of Kim Ju-yul was discovered in Masan Harbor. Kim - still dressed in his uniform from Masan Commercial High School - had disappeared in the March 15 clashes. Authorities claimed that he had drowned, but many Masan residents did not believe this explanation and forced their way into the hospital where Kim's body was stored. At the hospital, they discovered that grenade fragments behind his eyes had actually killed him. In the following days, mass demonstrations broke out involving as many as 40,000 residents throughout the characteristically politically left-leaning city. During renewed clashes with police, police opened fire and killed several protesters. Once again, the US military was called in to help restore order. At this point, public anger with the government had grown to new highs and rebellion against the Rhee government mushroomed around the country. Authorities subsequently declared martial law.
Thus, the events in Masan in 1960 helped spark the movement against corruption known as the April 19 Movement, which eventually led to the resignation of President Syngman Rhee and the beginning of the Second Republic.
1979 - Protests broke out in Masan (as well as in Busan) against the regime of President Park Chung-hee following a brutal police crackdown on a sit-in strike of female textile workers from YH Trading Company. Workers in Masan's Free-export Zone even managed to create four labour unions.
2009 - On December 7, the city council approved a proposal to merge Masan with Changwon and Jinhae, to form an as-then yet-to-be-named city of over one million people. The city councils of the other two cities had also approved the merger, which would bring national funds to the metropolis through a law designed to aid cities with populations of over one million. The Provincial Council of South Gyeongsang Province approved the merger, and a decision was expected to have been rendered in the penultimate week of December 2009.
Like most Korean cities, the city center of Masan is divided into administrative dong. Outlying regions are divided into 1 eup and 4 myeon:
Masan has three institutions of higher education: public vocational focused Masan University, which is located on the northwestern outskirts of the city in Yongdam-ri, and the private Kyungnam University (), which is located in the southern part of Masan adjacent to Shin Masan. And the small private Christian Chang Shin College,  in the northeastern part of the city.
The original central business district of Masan is located in Chang-dong. But recently it has moved to Hapseong-dong. Hapseong-dong is also a commercial neighborhood. An area with many bars, restaurants, and other forms of entertainment is located in Sinmasan.
Masan's baseball stadium  is the home of the KBO League's NC Dinos. It previously occasionally hosted the Lotte Giants, a Korea Baseball Organization team which plays in nearby Busan. A professional women's baseball team, one of several in South Korea, plays in Sinpo-dong. An amusement park and zoo are on the tiny island of Dot-do in Masan Bay. The park is only open in the summer.
Masan is also very close to Geojedo, a large island that can be reached by bus, car, or ferry.
Masan is generally known for its fishing industry and is the origin of spicy Agujjim, a steamed dish made with agwi (, blackmouth angler). Until the 1940s, the fish was not eaten and was frequently discarded due to its ugly appearance and low commercial value. However, as fish began to become more scarce in the late 20th century, the newly found delicacy became popular. Since its creation, agujjim has been considered a local specialty of Masan, especially around Odong-dong, one of the neighborhoods there and is favored by the public nationwide.
Masan is also home of a famous fish market (locally known as "Eosijang"). It is located near a street with a concentration of agujjim restaurants. A municipal officer of Masan city hall stated that it is the oldest and largest fish market in Gyeongsangnam-do, even older than Jagalchi Market in Busan.
Construction of the Machang Bridge commenced in the second quarter of 2004 and opened in mid 2008. The bridge alleviates congestion in Changwon by providing a link across Masan Bay. The bridge is 1.7 kilometers long.
Machang Bridge is the first large-scale bridge to be built in South Korea as a public-private partnership . The sponsors of the project, Bouygues Travaux Publics and Hyundai Engineering & Construction, had been pursuing the Project since the late 1990s. MCB Co., Ltd, the Concessionaire, is jointly owned by the sponsors and MKIF .
The port was once operated by the Mongolians (Yuan Dynasty in China) and used in the preparations to conquer Japan - which eventually failed. To this day, Masan features the small but historic "Mongojeong" (,) meaning Mongol Well. It is located on Jasan-dong 117, and represents the Mongolian influence on the city.
Today, Masan Port is one of the city's most dominating features. It was first opened in 1899. The port connects much of the outside world with the Changwon Industrial Complex, Masan's Free Trade Zone and the future Sachun Industrial Complex.
Jeodoyeonneukgyo Bridge is a popular spot to watch the beautiful sunrise and sunset. Built in 1987, the bridge connecting Gubok-ri and Jeodo Island is 182m in length and 15.5m in height. Rocks found on both ends of the bridge extend outward toward the sea, and one can cross the bridge while enjoying the beautiful backdrop of the deep blue sea.
This park is located in the heart of Masan, with a waterwheel along a 95m-long small stream, a pine trail created with red clay, an outdoor fitness area with gym equipment, a playground for children in the forest, an outdoor performance stage, and a gateball court.
This is a mural village where people can take a walk along a winding alley, and enjoy a view of a mountain village and the Masan Port. 32 artists painted the murals without pay as part of the efforts to invigorate the communities in Chusan-dong and Seongho-dong.