The Vlie or Vliestroom is the seaway between the Dutch islands of Vlieland and Terschelling. The Vlie was the estuary of the river IJssel in medieval times. In 1666 Admiral Robert Holmes burnt a Dutch merchant fleet of 150 ships (Holmes's Bonfire), that had taken refuge in the Vlie, mistakenly supposing the British could never find their way through the treacherous shoals, so typical for the coastal waters there.