HMS Dolphin was a 24-gun sixth-rate frigate of the Royal Navy. Launched in 1751, she was used as a survey ship from 1764 and made two circumnavigations of the world under the successive commands of John Byron and Samuel Wallis. She was the first ship to circumnavigate the world twice. She was constructed at the Woolwich Dockyards, England in 1751. Built by the Royal Navy suitable for war, she was classed as a sixth-rate, three-masted frigate in the rating system of the Royal Navy. Her length was 113 feet, breadth 32 feet, and she weighed 508 tons. A crew of around 160 was her usual complement, and she was fitted with twenty-eight 9-pounder and two 3-pounder guns. Dolphin was only the second sailing vessel to be fitted with copper sheathing.