The Alas Strait is a strait that separates Lombok and Sumbawa, the two principal islands of Indonesia forming West Nusa Tenggara province.

The strait was bridged by land until about 14,000 years before present when sea level rose to about 75 meters below present sea level, unlike Lombok Strait and Alor Strait which continued to be water gaps even during the Last Glacial Maximum, at each end of a 400-mile-long island including present-day Lombok, Sumbawa, Komodo, Flores, Solor, Adonara, and Lembata.