Floods of water originating from volcanically disturbed landscapes—volcanic water floods (VWFs)—differ from floods in most other types of drainage basins in the world in significant ways. They flow at higher discharges (flow rates), have higher flood peaks, and have shorter flow durations relative to watershed area than most other types of floods. They can have suspended-sediment concentrations that approach those of hyperconcentrated flow, and perhaps most importantly, they can transport such enormous amounts of sediment (suspended load and bed load) that rivers cannot transport all of it farther downstream. Resulting sediment storage in river valleys can result in channel aggregation and burial of valley floors by meters of sediment within hours or tens of meters within a few years. Small, short-duration VWFs in steep terrain often resemble dilute lahars—muddy floods moving as highly turbulent, very muddy water in multiple waves or surges down a channel. Larger, less concentrated VWFs behave more like muddy nonvolcanic floods but with greater-than-normal sediment transport rates. VWFs can be triggered by high-intensity or long-duration rainfall, rapid melting of snow and ice by volcanic eruptions, lake breakout floods, and glacial outburst floods. In highly disturbed watersheds, large-volume VWFs are likely to transform to lahars.