From left: Oris Blue Whale Limited Edition, 45.5mm, on multi-piece stainless steel bracelet with stainless steel security folding clasp. Part of the Oris Trilogy Set with the Oris Great Barrier Reef Limited Edition III and the Clean Ocean Limited Edition. Price of the Oris Trilogy Set: £7,560, oris.ch. Breitling Superocean Automatic, 42mm, in steel on Diver Pro III rubber strap, £2,760, breitling.com. Panerai Submersible Chrono PAM00614, 47mm, in brushed titanium on standard rubber strap, £13,100, panerai.com. Photograph: Sam Hofman/The Observer