In late March 2025, extreme rainfall in the Australian interior's drylands triggered major floods that inundated large parts of the desert. Rainfall totals within just a few days surpassed the average annual precipitation for large arid regions, exceeding 500 mm. Floods in the upper Kati Thanda-Lake Eyre (KT-LE) basin, one of the world's largest internal drainage systems, reached record levels. However, the basin's vast size complicates predictions about which portions of these floods will reach the terminal lake. Given the sparse stream gauges and the difficulty of measuring discharge where river widths span many tens of kilometers, how can we determine the flood magnitude across the basin? In this work, we quantify the spatial extent of river flows as a proxy for flow volume, allowing us to place it in a historical context. To achieve this, we utilized MODIS satellite imagery from 2000 to 2025, together with remotely sensed data from other Earth-surface and climate observation missions. Our analysis shows that the 2025 flood had the most extensive ephemeral surface water coverage in the basin over the past 25 years, with a maximum inundated area of approximately 38,000 km², comparable to the size of Switzerland (1.75 times Israel's land area). This area surpasses the previous maxima recorded during the major flood events in 2010 and 2011 by about 40%. In 2025, all three of KT-LE’s major tributaries experienced extensive flooding, with Cooper Creek experiencing the most extensive flood. On the other hand, because of its length, the flood in this river reached the lake more than 4 months after initiation, playing a minor role in the lake's active filling. Will the 2025 flood exceed the historical peak floods in the KT-LE basin in 1974? Answers will be revealed during the conference.