Understanding the physical or chemical parameters of a water body often requires the support of an off-site laboratory.  HELIX robots are capable of collecting physical samples for subsequent analysis.  A water sampler such as a Van Dorn is an open tube, 1L or 2L in size, lowered to a defined depth and triggered by a messenger system that closes both ends of the chamber, trapping the water sample within the device.  The sample is brought to the surface and custody transferred to human operators for further processing.  

Similarly, HELIX robots can deploy sediment samplers such as an Ekman grab sampler. This method uses two steel clamshells to grab the topmost layers of soil by cutting a bite from the soil. These underwater sediments can then be brought off site for analysis.