Al Siniyah Island is located approximately one kilometre east of Umm Al Quwain city, separated from it by Umm Al Quwain Creek. The island is about eight kilometres long and reaches a maximum width of four kilometres.

The island holds considerable historical significance. Around 200 years ago, the residents of Umm Al Quwain settled there after moving from Malaḥ Island under the leadership of the late Sheikh Majid bin Rashid Al Mualla. The inhabitants subsequently moved from Al Siniyah Island to the present-day city of Umm Al Quwain.

The island has a predominantly flat landscape, with mangrove and ghaf trees and low-growing vegetation. It is also a nature reserve inhabited by gazelles and various bird species, including gulls, eagles, herons and cormorants.

Al Siniyah Island is of great archaeological importance, containing 65 archaeological sites comprising tombs, structural remains, shell mounds and towers.