The Patek Philippe Nautilus was first introduced in the 1970s as a water resistant luxury sports watch. The original designer, Gérald Genta, based aspects of the timepiece's appearance on ship portholes and this remains a defining characteristic of the Nautilus collection to this day. As the collection has expanded, buyers have been able to make a decision between various different Nautilus models, made from a variety of materials. Stainless steel models within the Nautilus collection have a classic, enduring appeal, similar to that of the '70s Nautilus watches. At that time, the concept of a luxury sports watch made from steel was considered a bold approach, but it is more commonplace today and the collection has stood the test of time. Aside from its visual appeal, the stainless steel used by Patek Philippe is durable, affordable and easy to clean. Models within the stainless steel Nautilus category vary significantly, with complications including date displays, moon phase indicators and dual time zones. Black, blue and white dial colors are available, providing different looks, but all steel Nautilus watches share the same distinctive porthole-like shape and elegant, sporty aesthetic.