Ultra-clean, deep underground laboratories provide ideal conditions to search for astrophysical neutrinos, for the very rare radioactive process called Neutrino-less Double Beta Decay (0nbb) and for Dark Matter in the form of Weakly Interacting Massive Particles (WIMPS). University of Washington scientists played a major role in the Sudbury Neutrino Observatory (SNO) experiment that observed solar neutrino flavor change. The SNO detector has been repurposed as SNO+ to provide a sensitive search for 0nbb in 130Te. Liquid argon is being used as a target for very sensitive searches for WIMPS in our Galaxy in the DEAP and DarkSide experiments. Liquid argon has a valuable property that nuclear recoils from WIMPS would emit light over 200 times more quickly than betas or gammas, enabling significant discrimination against those backgrounds. Details of these experiments and the motivation for them in terms of fundamental physics and cosmology will be discussed.