Given that Langkawi Port is located in an archipelago composed of 99 islands, there are plenty of nearby beaches. The most popular beach is Pantai Cenang, which is at the end of Jalan Beringin road. From the port, head toward Jalan Beringin (Highway 160) and drive south until you reach the most southwestern tip of the island, where you will have 2 km (1.2 miles) of sandy beaches. Within walking distance and next to Pantai Cenang, you can also find Pantai Tengah, which is a good alternative for families who want a quieter environment.
For more info, see Langkawi Port Guide