Niskin3D: the open-source water sampler

**Niskin3D is low-cost, open-source water sampler made from 3D-printed parts and controlled by a waterproof servo.**

The Niskin bottle, a seemingly simple tube designed to take water samples at discrete depths, is one of the most important tools of oceanography. Coupled with a CTD, an array of Niskin bottles fit into a rosette provides everything an oceanographer needs to profile the ocean. Niskin bottles are neither cheap nor particularly easy to use. A commercial rosette requires a winch to