Antenna download weather and navigation data from satellites and feed it directly into shipboard systems. Instruments go into the water to collect water and bottom core samples, sea surface temperatures, sound velocity, water depth and current speed. Oceanographers on board the ship can't see the ocean floor, so they sweep over it with pulses of sound called sonar to create images of the undersea world. The sound reflects off submerged objects back to the surface and is recorded by equipment, giving oceanographers a picture of the size and shape of objects on the seafloor. Sonar can tell the difference between natural ocean floor features, like rocks, which generally have smooth rounded edges and manmade objects, like ship or aircraft wreckage, which generally have sharp defined edges.
Some sonar systems make it possible to continuously chart a broad strip of the ocean floor.
The oceanographic survey ships USNS Pathfinder, USNS Sumner, USNS Bowditch, USNS Henson and USNS Bruce C. Heezen can collect information in either deep or shallow water. The hydrographic survey ships, USNS John McDonnell and USNS Littlehales, gather information along coastlines for creating and updating nautical charts. USNS Bruce C. Heezen is the Navy's only oceanographic survey ship to be named by American schoolchildren. The Navy authorized the shipnaming contest during 1998, the Year of the Oceans. R.I. They named the ship after a famous oceanographer from Columbia University's Lamont-Doherty Earth Observatory.