Rocky planets orbiting M-dwarf stars are among the most promising and abundant astronomical targets for detecting habitable climates. We are especially interested in water worlds, a category of planets defined by the presence of liquid water, which is a minimum requirement for life as we know it. Water can shape the climate through a variety of mechanisms that are well-understood for Earth. However, many of these processes are wavelength-dependent, such that fundamental climate feedbacks behave differently on M-dwarf planets, where stellar emissions peak in the infrared. In this talk, we will explore the climate of M-dwarf water worlds and their prospects for retaining water. We will also show that water-limited land planets may be common and especially promising in terms of sustaining temperate climates.