When Explorer was under construction in Halls shipyard in 1955, another vessel was under construction in Hall Russel at the same time. This ship was to be the Sir William Hardy, a fishery research vessel commissioned by the the Ministry of Agriculture, Fisheries and Food. Unlike Explorer, she was a diesel electric vessel and suffered teething problems with that technology in her early days.
In 1977 Sir William Hardy was purchased by Greenpeace UK and after a refit she was christened Rainbow Warrior.
In 1985 the Rainbow Warrior made passage to New Zeland to lead a flotilla of boats protesting against French nuclear testing at Mururoa Atoll. On the 10th July 1985 while Rainbow Warrior was moored in Aukland, French intelligence agents attached two explosive devices to her hull. The first device exploded causing the crew to evacuate the ship. Unfortunately the photographer Fernando Pereira returned to the ship to rescue his equipment when a second larger explosion sank the ship and killed Fernando.