We present the first measurements of N₂O across three mesoscale eddies in the eastern tropical South Pacific. Eddie's vertical structure, offshore transport, properties during its formation and near-surface primary production determined the N₂O distribution. Substantial depletion of N₂O within the core of anticyclonic eddies suggests that although these are transient features, N-loss processes within their centres can lead to an enhanced N₂O sink which is not accounted for in marine N₂O budgets.