The correlation function of localized Lommel-Gaussian vortex beams is obtained in oceanic turbulence and used to estimate the channel capacity of underwater wireless optical communication systems (UWOCS). The effects of laser source and oceanic turbulence on the channel capacity are discussed. Results show that the choices of appropriate light parameters, such as input pulse half-width, beam waist, and orbital angular momentum number, are essential to achieve high channel capacity in UWOCS. Another important factor that affects channel capacity is oceanic turbulence. Scaling analysis shows that inner scale has a more significant effect on the channel capacity than the outer scale does.