An air-cushion vehicle, or hovercraft, capable of traveling between Dover in England and Calais in France in about thirty minutes—without touching the water—was first used commercially by the United Kingdom as early as 1968. This vehicle, known as the SR.N4, was the largest passenger hovercraft in the world at the time. In its Mark III version, it measured 16.9 meters long and was powered by four Rolls-Royce Proteus gas turbines, each burning a ton of fuel per hour. The SR.N4 was designed to carry up to 60 cars and 418 passengers, a capacity comparable to that of a Boeing 747. It operated from four hoverports: Pegwell Bay and Dover in England, and Calais and Boulogne in France. The crossing, covering about thirty kilometers, typically took around 35 minutes, earning the hovercraft the nickname "Concorde of the Seas" for its speed and efficiency. An unofficial record of 22 minutes was set in 1995. The hovercraft service was particularly popular in its peak years, transporting 3 million passengers in a single year. At the time, the fast, high-speed crossings were a novelty for British vacationers, offering a unique and exciting way to cross the English Channel. However, the decline of the SR.N4 was not due to technical issues or bad weather, but rather economic factors. The opening of the Channel Tunnel in 1994 provided a direct, fast, and weather-insensitive rail alternative, which many travelers found more reliable. Additionally, the hovercraft sometimes had to cancel trips due to strong winds, making it less appealing than the train. The route eventually closed in October 2000, partly because of competition from the new rail service. Another factor in the SR.N4's decline was the end of duty-free sales on board in 1999. Duty-free products had been a major source of profit for the service, more so than ticket sales. As spare parts became harder to find, the hovercrafts were taken out of service. The end of the service was marked by the final commercial runs of two hovercrafts, the Princess Anne and the Princess Margaret, on October 1, 2000. These runs were witnessed by a crowd of onlookers. Initially, the two hovercrafts were stored at the Hovercraft Museum in Lee-on-the-Solent, Hampshire, but a real estate project threatened their preservation. A public petition in 2016 helped secure the future of one of the hovercrafts. In August 2016, the museum was granted a three-year lease to restore the Princess Anne in the original Seaspeed era livery. Its twin sister, the Princess Margaret, was dismantled in March 2018, with parts used to complete the restoration of the surviving vessel. Today, the Princess Anne remains the last surviving example of this class of giant hovercrafts. It is displayed in a museum that houses more than 60 hovercrafts of various designs, preserving the legacy of this once-revolutionary mode of transport.