The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (âˆ¼10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 Ã— 10-5, and 3.0 Ã— 10-3, respectively, which pass well the forward error correction (FEC) criterion. Â© 2016 Optical Society of America.