Selat Cincin is the channel 4 miles wide between the S end of Ko Tarutao and the N coast of Pulau Langkawi.

The channel trends SE around the NE side of Pulau Langkawi and is bounded on the NE side by the coastal bank off the coast of Thailand.

Tides—Currents.—The tidal currents in Selat Cincin are irregular and influenced by the monsoons. During the Northeast Monsoon rates of 2 knots setting WSW have been experienced.
Depths in the channel are regular, shoaling gradually ENE and towards each side, with depths of over 18m in the fairway.