Offering unique wavelength versatility, continuous-wave optical parametric oscillators (cw OPOs) are appealing sources of widely tunable laser light. Due to technical challenges, however, practical tunable cw OPO devices have so far been mostly limited either to near-infrared wavelength coverage or to maximum optical output powers in the 100 mW range-or both. We present a novel cw OPO design achieving output powers at the Watt-level throughout the very wide 500-765 nm gap-free tuning range in the visible and coverage of up to 3540 nm in the infrared spectral range. The system layout and its wavelength tuning options are tailored, in particular, to fundamental experiments in quantum and nanophotonics research as well as to applied holography.