The Lofoten Vortex is an unusual feature in the ocean: a permanent eddy which does not dissipate as most eddies do. We have long thought that other eddies must merge into the vortex in order to maintain its heat content and energetics, but such mergers are very difficult to observe due to their transient, unpredictable nature. For the first time, we have observed a merger using an ocean glider and high-resolution satellite data and can document how the merger affects the properties of the vortex.