The second most popular beach on Koh Tao, Chalok Baan Kao is overrun with the usual plethora of dive shops, guesthouses, restaurants, travel agents and bars, all of which line the main road running just off the back of the beach.
The beach here is pretty and at low tide passable for sunbathing, but really there are far better spots elsewhere on Koh Tao for laying around in the sun - just by hiking over the headland to Ao Thian Og will deliver you to a lovely strip of sand all to yourself.
Due to Chalok Baan Kao being one of the largest dive centres on Koh Tao, a lot of boat traffic heads in and out throughout the day. Be it divers coming and going, snorkelling trips, round-the-island boat trips, fishing trips or just longtails off on taxi runs from here, Chalok is not one of Koh Tao's quieter strips of sand.
The large number of boats also contributes to the water being a bit murky, particularly towards the western end of the bay. Head to the eastern stretch of the beach if you plan to spend any time in the water, but if time allows, you're far better served to wander off to another nearby beach. Chalok Baan Kao is flanked by beaches and bays to both the east and west, so you need not head too far to find something pretty.
On its western lip, at the beginning of the trail around to Mae Haad, you'll find the very pleasant Haad Saal Chao. This spot remains a pleasant area to hang out, despite the sometimes cloudy waters.
Along the eastern rim, running along the peninsula which separates Chalok Baan Kao from Ao Thian Og, you'll find Ao Taa Toh which has a single, dive orientated resort and further along the lovely and very isolated Freedom Beach. Both of these have clean beaches and clear waters.