The MSM-03 Gogg is an amphibious mobile suit introduced in Mobile Suit Gundam.

The Principality of Zeon had developed the ground use MS-09 Dom, but its nuclear reactor's output was insufficient for powering mega particle cannons/guns. Increasing the reactor output would require better cooling capacity, and the most efficient method was water cooling. Therefore, in November U.C. 0078, the MIP and Zimmad received orders to develop amphibious MS which can use seawater for cooling. In addition to the use of mega particle weapons, the amphibious MS can reach its destination by traveling through the sea on its own, allowing it to fight in areas away from Zeon's frontline bases.

To reduce water resistance, the Gogg's head became a rounded streamline shape, the MS' equipment was internalized, and the limbs can be retracted when cruising underwater. The Gogg has long operating time in water, and relies on thermonuclear hydrojet engines that draw in water, then heat them with the high heat of the reactor to create thrust. When operating on land, cooling water is stored in internal ballast tank, and the mobile suit's operating time is limited to 1–2 hours. This shortened operating time on land is due to reactor cooling limitations. The Gogg is not an agile machine due to its weight, but its pressure-resistant design provides sufficient defense in close combat.

The Gogg's design proved marginally successful, and about 300 units were produced according to one source.[1] However, it would be later replaced by more powerful and better designed amphibious mobile suits, such as the MIP's highly successful MSM-07 Z'Gok. Despite this, the Gogg served as a base design from which almost all other underwater combat mobile suits were derived.