 It is separated from the Outer Hebrides by the Rockall Trough, itself located within the Rockall Basin (also known as the "Hatton Rockall Basin").In 1956 the British scientist James Fisher referred to the island as "the most isolated small rock in the oceans of the world".The neighbouring Hasselwood Rock and several other pinnacles of the surrounding Helen's Reef are smaller, at half the size of Rockall or less, and equally remote, but those formations are legally not islands or points on land, as they are often submerged completely, only revealed momentarily above certain types of ocean surface waves.