A sedimentation trap for use just above the deep-sea floor was free-fallen to a depth of 2050 m in the Tongue of the Ocean canyon on January 3, 1974. On March 6, it was successfully recovered with the assistance of D.S.R.V. Alvin. The trap has a base 1 m square and a height of 30 cm. At the trap bottom are filters to retain falling particles. Two spring-powered sliding doors, each 1 m × 0.5 m, are used to close off the lower 2 cm of the trap during ascent to prevent disturbance of the particles collected on the filters....