Tudor - Pelagos
The 42mm case of this timepiece (inquiries: 2249 8833) is made of titanium and steel with a satin finish. Water-resistant to 500 metres, it has a helium valve for pressure changes and a black ceramic unidirectional rotating bezel with luminescent numerals. The titanium bracelet and additional rubber strap can extend if being worn over a wetsuit.
Omega - Seamaster Planet Ocean Ceragold
This watch (HK$258,300) has a polished black ceramic bezel and the diving scale is made of Ceragold (a blend of gold and ceramics). Water-resistant to 600 metres, it has a unidirectional rotating bezel and a helium escape valve. On the lacquered black dial, the 60-minute and 12-hour counters are presented on the sub-dial at 3 o'clock, and the sub-dial at 9 o'clock shows the seconds.
Oris - Kittiwake Limited Edition
This watch (HK$26,000) is named after Kittiwake, an artificial reef off Grand Cayman created by the deliberate sinking of the USS Kittiwake. It is water-resistant to 1,000 metres. Numerals engraved on the bezel indicate elapsed diving time. The case back is engraved with a serial number. The titanium bracelet has a security folding clasp and extension system.