This paper presents simulation results for an underwater optical wireless communication system based on light emitting diode (LED) and integrated detector preamplifier (IDP). Both the position and the orientation of the transmitter and the receiver change during the swimmer's actions. The simulation results showed the line of sight (LOS) communication link and the non line of sight (NLOS). The effect of air bubbles in water which was studied by the authors previously was included in the simulation as a swimmer generates a huge amount of bubbles during swimming. The received power and the link margins for two different LEDs were calculated to check the availability of the system. It was proven that the half power beam width (HPBW) and the bubbles are important factors in the link budget calculations and this is important for the link availability. The simulation results for the optical wireless system using a superflux LED and OPT101 receiver achieved more than 1 m communication link underwater with and without the effect of air bubbles.