Abstract: The discovery of neutrino oscillation, which leads to a non-zero neutrino mass, creates a host of interesting questions with relevance to particle physics, astrophysics, cosmology and beyond. After a brief review, I will cover some of the major oscillation topics and how the DeepCore sub-array, a low-energy extension of the IceCube neutrino observatory, offers new opportunities for neutrino oscillation physics in the tens of GeV energy region. Possible future extensions designed to drive the energy reach down to ~1 GeV in an initial stage (PINGU) and tens of MeV in a second stage (MICA) will conclude the talk.<br>