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The ability to spectrally translate lightwave signals in a compact, low-power platform is at the heart of the promise of nonlinear nanophotonic technologies. For example, a device to connect the telecommunications band with visible and short near-infrared wavelengths can enable a connection between high-performance chip-integrated lasers based on scalable nanofabrication technology with atomic systems used for time and frequency metrology. While second-order nonlinear (chi^(2)) systems are a natural approach for bridging such large spectral gaps, here we show that third-order nonlinear (chi^(3)) systems, despite their much weaker nonlinear coefficients, can realize spectral translation with unprecedented performance. By combining resonant enhancement with nanophotonic mode engineering in a silicon nitride microring resonator, we demonstrate efficient spectral translation of a continuous-wave telecom signal at 1573 nm to a visible wavelength at 670 nm through cavity-enhanced four-wave mixing. We achieve translation over a spectral range over 250 THz and a translation efficiency of (30.1 +/- 2.8) % using only (329 +/- 13) μW pump power. The translation efficiency projects to (274 +/- 28) % at 1 mW and is more than an order of magnitude larger than what has been achieved in current nanophotonic devices.