Advances in neutrino physics and direct dark matter searches call for even more massive underground detectors than the current state-of-the-art. However, the physics potential of these experiments stretches far beyond their primary targets. I will illustrate this through two complimentary programs of research, portraying dark matter detectors as effective neutrino telescopes and neutrino detectors as laboratories for physics beyond the Standard Model. As I will show, using neutrinos, future dark matter experiments could potentially offer new insights into Earth's formation as well as forecast of supernovae. On the other hand, large water Cherenkov neutrino experiments can explore a variety of theories beyond the Standard Model through baryon-number violating processes and millicharge particles. More so, through studies of sterile neutrinos, they could shed light on the Hubble constant tension problem that mystifies the expansion of the Universe.