The presence of a pore fluid is recognized to significantly increase the mobility of saturated over dry granular flows. However, experimental studies in which both the bulk-scale (runout) and grain-scale behaviour of identical granular material in a dry and saturated initial state are directly compared are rare. Further, the mechanisms through which pore fluid increases mobility may not be captured in experimental flows of small volume typical of laboratory conditions. Here we present the results of dry and initially fluid saturated or ‘wet’ experimental flows in a large laboratory flume for five source volumes of 0.2 to cubic metre. Our results demonstrate that the striking differences in the nature of interactions at the particle scale between wet and dry flows can be directly linked to macro-scale behaviour: in particular, a greatly increased mobility for wet granular flows compared to dry, and a significant influence of scale as controlled by source volume. This dataset provides valuable test scenarios to explore the fundamental mechanisms through which the presence of a pore fluid increases flow mobility by first constraining the frictional properties of the material (dry experiments), permitting an independent evaluation of the implementation of interstitial fluid effects in numerical runout models (wet experiments).