This small island is a Site of Special Scientific Interest.

It is owned and managed by the Wildlife Trust of South and West Wales and is the site of the United Kingdom's first bird observatory.

The present lighthouse was constructed over several years up to 1915 and was officially opened in 1916.

Forming a triangle of lights with South Bishop and the Smalls to protect shipping moving into and out of Milford Haven and the Bristol Channel, the lighthouse shines 20 miles (32 km).

This enabled building materials to be landed, which were then moved to the site using a narrow gauge railway, initially powered by a donkey, then a pony, and finally a tractor.