Casio G-Shock, GA-2100: £119 The original 1980s G-Shocks were tough, but that was about it. Today's models are even tougher – this one gets a patented carbon-reinforced resin case – but also cater to more expressive tastes, like this 200m water resistant camo edition. Sinn U50: £1,890 This German brand was founded in the 1960s and is known for no-nonsense tool watches. The U50 diver has an automatic movement and a case made from seawater-resistant submarine steel.