Methane (CH₄) seepage is the steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs that has been identified as a significant source of atmospheric CH₄. The monitoring of these emissions is important and despite several available methods, large macroseeps are still difficult to measure due to a lack of a lightweight and inexpensive method deployable in remote environments. Here, we report the development of a mobile chamber for measuring intense CH₄ macroseepage in lakes.