Marine mammals often forage in dark or turbid waters. Whereas dolphins use echolocation under such conditions, pinnipeds apparently lack this sensory ability. For seals hunting in the dark, one source of sensory information may consist of fish-generated water movements, which seals can detect with their highly sensitive whiskers. Water movements in the wake of fishes persist for several minutes. Here we show that blindfolded seals can use their whiskers to detect and accurately follow hydrodynamic trails generated by a miniature submarine. This shows that hydrodynamic information can be used for long-distance prey location.