After the 40th anniversary of the Nautilus in 2016, Patek Philippe is celebrating a new milestone this year as the Aquanaut turns twenty. The new Reference 5168G is the first men's model in the collection to be proposed in white gold, a metal recognisable as having a much warmer sheen than steel. The design is unchanged: a rounded octagonal bezel with vertical brushing on the top mixed with chamfered and polished sides. What is new is the 42-mm diameter, making it the largest Aquanaut. Ticking away inside is the 324 SC calibre, an automatic movement with a remarkable 3.30-mm profile and Haute Horlogerie finishes.