 This strait, which had been foreshadowed by Abel Tasman in 1642, proved that New Zealand was an archipelago and not part of the imagined Southern Continent.Cook sighted Foveaux Strait during his circumnavigation of the South Island in March 1770 but, Margaret Cameron-Ash has argued, decided to hide it.The Admiralty had issued its usual instructions to hide strategically important discoveries that could become security risks, such as off-shore islands from which operations could be mounted by a hostile power, such as France.