Holothuroidea represent the dominant benthic megafauna in hadal trenches (~6,000-11,000 m), but little is known about their behaviour and functional role at such depths. Using a time-lapse camera at 8,074 m in the Peru-Chile Trench (SE Pacific Ocean), we provide the first in situ observations of locomotory activity for the elasipodid holothurian Elpidia atakama Belyaev in Shirshov Inst Oceanol 92:326-367, (1971). Time-lapse sequences reveal 'run and mill' behaviour whereby bouts of feeding activity are interspersed by periods of locomotion. Over the total observation period (20 h 25 min), we observed a mean (±SD) locomotion speed of 7. 0 ± 5. 7 BL h -1, but this increased to 10. 9 ± 7. 2 BL h -1 during active relocation and reduced to 4. 8 ± 2. 9 BL h -1 during feeding. These observations show E. atakama translocates and processes sediment at rates comparable to shallower species despite extreme hydrostatic pressure and remoteness from surface-derived food.