Vatersay is irregularly shaped and has a tombolo: it is composed of two rocky islands (north and south) linked by a sandy isthmus.

The island has remains of an Iron Age broch at Dun a' Chaolais overlooking the Sound of Vatersay, and nearby is a passage grave dated to the 3rd millennium BC.

[10] There is also a Bronze Age cemetery at Trèseabhaig south of the heights of Heiseabhal Mòr[11] and a cairn built around 1000 BC west of the village of Vatersay.

After much public protest at these events, in 1909, the Congested Districts Board (Scotland) bought Vatersay island for £6250 (equivalent to £823,000 in 2023),[14] and it was divided into 58 crofts.

[15][16] In September 1853, the Annie Jane, a three-masted migrant ship out of Liverpool bound for Montreal, Quebec, Canada, struck rocks off West Beach during a storm.

[18] The remains of a Catalina flying boat that crashed on the slopes of Heiseabhal Beag in 1944 lie in a stream bed near the shore.