A single-shot ultrashort pulse off-axis digital holography (UPODH) system successfully images microscopic details of fuel injection phenomena that are hidden from normal optical view by a dense cloud of droplets surrounding the near-nozzle region. The experiment approximates the optically dense conditions typical of fuel injection in modern diesel engines. Under these conditions an outer layer of small droplets can hide a core of larger droplets or liquid ligaments; this core is inaccessible to most imaging techniques due to multiple scattering in the outer layer. These conditions are mimicked by intentionally surrounding a core spray with a fine mist. The mist has a Sauter mean diameter of 4.28 micrometers. The core spray comes from driving water, with pressure ranging from 1 to 13.8 bar, through single orifices of 0.1 and 0.3 mm diameter. The spray field shows nearly opaque transmissivities as low as 6 x 10(-6). Transient phenomena, such as sheets of liquid becoming ligaments and their further breakup into small particles, are easily visible even when surrounded by the opaque mist with an optical density (OD) of 12. Holographic reconstruction allows these phenomena to be clearly observable in 3D, and single droplets as small as 25 mu m are identifiable. The 3D capability allows UPODH to bring into focus small particles and ligaments at different depth planes, even centimeters apart.