hydrocast

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The process of using a device consisting of several water-collection bottles, such as Nansen bottles, that are wired and clamped together and used to collect data on water characteristics at various depths.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A form of scientific water measurement in which several connected bottles are lowered into the water to collect samples.