The dynamics of marine-terminating outlet glaciers on the Greenland Ice Sheet are of crucial importance with their principal role in draining the ice sheet. Much work has focused on determining the processes and mechanisms influencing their flow, with most focus on terminus processes, whilst little attention has been paid to the effects of hydrological processes via surface runoff and supraglacial lake drainage. There has been increasing evidence for the influence of enhanced meltwater inputs on impacting short term velocity at marine-terminating outlet glaciers with contrasting responses at individual glaciers. This study uses a remote sensing approach to characterise supraglacial lakes and their volumes at Store Gletscher and Rink Isbrae, two marine-terminating outlet glaciers in West Greenland, to assess the influence of such processes on their flow, providing an effective comparison due to their contrasting geometries, despite similar environmental controls. At Store there is evidence of a strong influence of hydrological mechanisms on its summer velocity variability, supporting observations in previous work with a transition to efficient drainage. However, the opposite is identified at Rink. This difference is suggested to be caused by Rink’s lower capacity for lake formation with a steeper hypsometry and narrower ablation area compared to Store, reflecting the primary controls of surface topography and surface runoff volume on lake formation. These conclusions reveal the possible significant influence of hydrological mechanisms on flow at marine-terminating margins, whilst also indicating a probable range of responses at different glaciers dependent on glacier-specific factors.