The advent of the quantum gas microscope allowed for the in situ probing of ultracold gaseous matter on an unprecedented level of spatial resolution. However, the study of phenomena on ever smaller length scales, as well as the probing of three-dimensional systems, is fundamentally limited by the wavelength of the imaging light for all techniques based on linear optics. Here, we report on a high-resolution ion microscope as a versatile and powerful experimental tool to investigate quantum gases. The instrument clearly resolves atoms in an optical lattice with a spacing of 532 nm over a field of view of 50 sites and offers an extremely large depth of field on the order of at least70μm. With a simple model, we extract an upper limit for the achievable resolution of approximately 200 nm from our data. We demonstrate a pulsed operation mode enabling 3D imaging and allowing for the study of ionic impurities and Rydberg physics.