LOCATION: Located at the northernmost point of Langkawi Island. On clear days, you can see a number of islands within the Thailand’s border such as Ko Turatao and Ko Adang.
DESCRIPTION: One of the most popular beach in Langkawi, playing host to two of the most expensive resorts on the island, name the Four Seasons Langkawi and Tanjung Rhu Resort.
To me, the biggest attraction of Tanjung Rhu beach is probably the interesting limestone formations of the nearby islands. There are a number of small boat operators offering tours to the limestone islands - to see the vegetation, the dark caves, possibly some small animals, etc.
It is claimed at one of the islands, called Dangli Island, hosts some nice coral for snorkeling, but I have a feeling that the visibility is not so good, judging from the condition of the beach itself and its close proximity to the mangrove river that meets the Andaman Sea at Tanjung Rhu.
BURAU BAY LOCATION: Burau Bay, or locally known as Teluk Burau, is located some 20 minutes from Langkawi International Airport (LGK) or 45 minutes from Kuah town.
The only way to get here is by the island’s taxi which can cost you about RM20-30 per way. If you intend to circle the island of Langkawi itself, it is more cost-saving to rent a car that goes for anywhere between RM80 to RM150 per day, depending on the car model.
DESCRIPTION: A fairly secluded bay in Langkawi. While Burau Bay is regarded as a public beach, the crowds only come from those who patron either Mutiara Burau Bay Resort or Berjaya Langkawi Resort. These resorts flank the opposite ends of Burau Bay.
The beach itself is very long. I estimate that it might take a 2-km walk from end to end. The water can be considered pleasant to swim in and not as murky as most beaches in Langkawi.
The view from the beach is spectacular, with the jagged peaks of the Gunung Mat Chinchang nearby creates an awe-inspiring backdrop.
The information on Malaysian Islands is provided by:
ISLANDS OF MALAYSIA The Independent Travel Guides to Malaysian Islands
Adang.
formations of the nearby islands. There are a number of small boat operators offering tours to the limestone islands - to see the vegetation, the dark caves, possibly some small animals, etc. 
The water can be considered pleasant to swim in and not as murky as most beaches in Langkawi. 