The peak-to-average power ratio (PAPR) reduction schemes are studied for underwater wireless optical communication system (UWOC), which adopts orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) in visible light communication (VLC). Based on the tone reservation (TR) technology, the proposed SCRLSA method is compared with the classic Clippling method and the least squares approximation (LSA) method over the UWOC channel model. Simulation results show that with the distances ranged from 1 meter to 15 meters, the proposed SCRLSA method has better bit error rate (BER) performance than the Clipping method and the LSA method for underwater communication. Moreover, the proposed method can reduce the PAPR by 4dB compared with the original OFDM signal.