The Niskin bottle, a seemingly simple device designed to take water samples at discrete depths, is one of the most important tools of oceanography. These precision instruments allow us to bring ocean water back to the surface to study its chemical composition, quality, and biologic constituency. If you want to know how much plastic is circulating in the deep sea, you need a Niskin bottle. If you need to measure chemical-rich plumes in minute detail, you need a Niskin bottle. If you want to use environmental DNA analyses to identify the organisms living in a region of the big blue sea, you need a Niskin bottle.
Niskin bottles are neither cheap nor particularly easy to use. A commercial rosette requires a winch to launch and recover, necessitating both a vessel and a crew to deploy. For informal, unaffiliated, or unfunded researchers, as well as citizen scientists or any researcher working on a tight budget, getting high-quality, discrete water samples is an ongoing challenge.