Thermopylae was built in Walter Hook's yards in Aberdeen in 1868, to the order of George Thompson & Co of London. Designed by Bernard Waymouth, she was 212 feet long and registered at 947 tons. A splendid sea boat, she was fast in any weather and especially quick at going to windward. Launched on 19 August 1868, she sailed from Gravesend on her maiden voyage to Melbourne on 7 November the same year. Anchoring in Port Phillip after a record run of 60 days (pilot), she went straight on to Newcasle, NSW, to load cargo for Shanghai crossing the Pacific in another record passage of 28 days, she then proceeded to Foochow to load tea. In the race home, she narrowly missed setting the record time for the year, and this first voyage set the standard for her entire career. Continuing to make extremely fast passages throughout the 1870s, she loaded her final tea cargo at Foochow in 1881, before being transferred to the Australian wool route. During the 1880, she frequently raced her old tea-trade rival Cutty Sark from Sydney to London, via Cape Horn. Her best passage was 76 days in 1882, although Cutty Sark, who revelled in the stronger winds of the southern hemisphere, was generally quicker.

In 1890 Thermopylae was sold to Canadian owners for 5,000 pounds sterling and from 1892 to 1895 she was used in the trans-Pacific trade. In 1896 she was resold to the Portuguese Government, renamed Pedro Nunes and put to work as a training ship. Her condition deteriorated gradually and by 1907 her working life was over. On 13 October that year, she was towed out of the Tagus into the open sea and sunk by gunfire; it was a sad and for such a thoroughbred as she. Considered by many to have been the fastest clipper of them all, there were even those who believed her to be the fastest sailing vessel ever launched. Whatever the truth of the claims, she was - and has remained - one of the legends of the age of sail.