Single-malt Scotch whisky-- Glen Ord's Singleton, to be exact. This is a special whisky glass from the Glen Ord distillery in the Black Isle region of Scotland.
The word "whisky" derives from the Scottish Gaelic "uisge beatha", meaning "lively water" or "water of life". So even though this is not exactly plain water, it certainly is lively!
(OK, one small confession. This is simulated Scotch. You think I'd waste expensive single-malt Scotch pouring it 57 times into, and around the glass for this picture?!)