This horticultural miracle of an island was created in the early 20th century when the island's owner commissioned architect Harold Peto to design a garden on the then-barren outcrop. Topsoil was shipped in, landscaped gardens laid out, and subtropical species planted; camellias, magnolias and rhododendrons now provide a seasonal blaze of colour. Harbour Queen and Blue Pool run 10-minute ferry trips to the island past colonies of basking seals and a nesting site for white-tailed eagles.
The centrepiece of the island is a magical Italianate garden; nearby a cypress avenue leads to a faux-Grecian temple with a stunning view of Sugarloaf Mountain. There are more views from the island's highest point, a 19th-century Martello tower, one of hundreds built around the coast to watch out for a possible Napoleonic invasion.