Seven of the "best known" opium clippers go missing in 1849: Sylph, Coquette, Kelpie, Greyhound, Don Juan, Mischief, and Anna Eliza.

Sylph was a clipper ship built at Sulkea, opposite Calcutta, in 1831 for the Parsi merchant Rustomjee Cowasjee.

After her purchase by the Hong Kong-based merchant house Jardine Matheson, in 1833 Sylph went on to set an unbroken speed record by sailing from Calcutta to Macao in seventeen days, seventeen hours.

Her primary role was to transport opium between various ports in the Far East.

She disappears en route to Singapore, possibly captured and burned by pirates based on Hainan Island.

Other sources believe that she was shipwrecked on the rocks of Pedra Branca off the coast of Singapore while carrying a cargo of opium to the value of five hundred and fifty seven thousand two hundred Spanish dollars.