Oh my... I feel, that I should convert into "Cocktail-Mythbusters". Apparently there is a "competition out there" for the coldest Martini cocktail. This is... dumb. There are bars, which are using super-chilled water, to dilute a mixture of freezer Martini premix or just gin or vodka. This is counterproductive (because of... science). Water doesn't become much colder than 0ºC. And super chilled it is max -5ºC - but doesn't really store the thermal capacity (because water has a freezing point and the "naturally coldest" temperature of 0ºC). All what you do is increasing the temperature of the drink. Oh - there are also different ways . Point is, that these are gimmicks. If you really need to, put a bottle of premixed martini (super-super dry, vermouth has less alcohol, means, it increases the freezing point of the water-ethanol solution) into a specialty freezer, which goes below -20ºC. But as Dave Arnold have pointed it out - a too cold cocktail ...