Boardwalk Hall Auditorium Organ, Pipe organ in Boardwalk Hall, Atlantic City, New Jersey, US

The Boardwalk Hall Auditorium Organ, known as the Midmer-Losh, is a pipe organ in the Main Auditorium of Boardwalk Hall in Atlantic City, New Jersey. Its pipes, officially 33,112, are hidden behind decorative grilles in eight chambers around the hall, so no pipes are visible from the public space. Its main console has seven manuals and 1,235 stoptabs.

Designed by state senator Emerson Richards and built by Midmer-Losh of Merrick, New York, as opus 5550, the organ was assembled from May 1929 to December 1932. The Depression bankrupted Midmer-Losh, Richards and Atlantic City, delaying work; it was first played publicly on 11 May 1932. The 1944 Great Atlantic Hurricane badly damaged it.

The organ was mostly used to accompany entertainment events, the Miss America pageant, political rallies and sports, and only rarely as a concert instrument. Since 2019 the seven-manual main console is named for Frederick R. Haas, whose family foundation funded its restoration. Half-hour organ demonstrations are held at midday Monday to Friday, free of charge.

No pipes are visible from the auditorium; the divisions sit in eight chambers behind the walls, and the 7-manual console is the closest a visitor gets to the instrument. Half-hour organ demonstrations are held at midday Monday to Friday with free admission. The older 5-manual console stands in the lobby outside the auditorium, no longer connected.

The Grand Ophicleide, in the Pedal Right division behind the Right Stage chamber grille, speaks on 100 inches of wind pressure and is listed by Guinness World Records as the loudest organ stop. The organ holds four Guinness entries, among them largest and loudest musical instrument. Its 64-foot Diaphone-Dulzian is one of only two open 64-foot ranks in the world.