Science Center Objects

PCMSC uses the GOMEX box corer for collecting soft, deep-water sediment samples.

A stainless steel box coring device for sampling sediment sits on the deck of a boat.

GOMEX box corer

The GOMEX box corer is constructed of stainless steel and is used to sample soft sediments at the bottom of lakes, bays, and the ocean. The GOMEX box coring sampler is so-named because it is popular for sampling work in the Gulf of Mexico. Trays on either side of the GOMEX hold lead weights, which serve as ballast to help the corer to drop smoothly and straight through the water column. When the corer makes contact with the ocean floor, the weights help drive the box into the soft sediment. The box sinks neatly into the sediment with minimal sediment disturbance. The force of hitting the bottom triggers a tripping mechanism that frees up two hinged doors, called spades. As the box corer is raised, the lead weights again help to push the spades closed and hold them closed so that the sediment stays in the box.

The GOMEX is easy to use, has a large sampling volume for its size, and it can be deployed off smaller vessels or where space is limited.  The advantages of the GOMEX corer are its tripping and closing mechanisms, as well as its light weight and small size.


  • Manufacturer – Ocean Instruments
  • Model – GMX-25 Gomex Box Corer Standard
  • Weight – 80 lbs (36 kg) bare, with 160 lbs of modular weight in 20-lb bricks.
  • Dimensions
    • Height: 100 cm
    • Deck footprint: 30×30 cm
    • Box area: 25 cm X 25 cm X 50 cm
    • Sampling area: 625 cm2
  • Power requirements - None
  • Safe working load - 250 lbs

Operational Characteristics

  • Operational depth – Unlimited, but most successful in water depths between 5 and 100 meters.
  • Sediment type – Soft, deep-water sediments
  • Limitations – Its light weight lends to kiting in deep water; and its box is not removable, so all sub-sampling must happen in situ.
  • Vessel requirements – Small davit or A-frame, winch, ability to hold station for ~30 seconds.
Five people on a small boat in calm water work on a sampling device being retrieved from the water.

USGS science crew works to free the muddy sediment from a GOMEX box corer while on PCMSC's vessel Jewell on Grizzly Bay in the San Francisco Bay area.