Heleysundet (English: Heley Sound) is a narrow sound between Kükenthaløya and Spitsbergen. It is known for its violent tidal races.
Heleysundet was discovered (and named) by the 60-ton ship John Ellis in 1617, which had been sent out by the Muscovy Company to explore to the south-eastwards of Spitsbergen. The sound was named after the Englishman William Heley (b. 1594/95), a supercargo and vice-admiral of the English whaling fleet from 1617 to 1623.
Coordinates: 78°30′N 21°00′E / 78.500°N 21.000°E