We present an inexpensive autonomous underwater pumping system that is lightweight, compact, independent, and versatile, making it easy to deploy in a multitude of settings. This system can be used to pump water into discrete and flow-through sensor systems. With the exception of the custom built pressure case housing, this system can be fabricated with off-the-shelf parts, making it easier to maintain. This system uses open source Arduino software code for easier customization and operations. The electronics and battery pack used to power this system can be adapted to fit into commercially available pressure case housings.