Visible light communication (VLC) has the ability to provide a high data rate up to Mbps in underwater environments for real-time communication systems. In underwater VLC (UWVLC), two major impairments are the turbulence-induced fading due to variation of salt and temperature of seawater and incremental path loss with distance due to absorption and scattering. We consider these two impairments and derive the closed form expressions for average symbol error probability (ASEP), asymptotic relative diversity order, and ergodic capacity for UWVLC dual-hop cooperative communication system. We consider multiple receiver branches with selection combining to combat the effect of fading. The impact of temperature on the fading parameters and system performance is highlighted. We conduct a comparative analysis of ASEP for four-pulse amplitude modulation and four-square quadrature amplitude modulation schemes and draw useful insights. We prove the accuracy of the derived analytical expression using Monte Carlo simulations.