Warming ocean currents are considered to be a contributing factor to the retreat of marine-terminating glaciers worldwide, but direct observations near the ice–ocean interface are challenging. We use radar intensity imagery and an iceberg tracking algorithm to produce half-hourly current maps within an imaged portion of Jökulsárlón, a proglacial lagoon in southeastern Iceland. Over our 43.5-h observation period, the lagoon has clockwise circulation with current speeds of order 3–8 cm/s and occasional strong glacier outflows of up to ∼15 cm/s. The currents driven by the glacial outflows appear to be dominantly inertial.