As tough as the Rolex Sea-Dweller 4000 is, it will not protect you from sharks or jellyfish.

Now for the good news: if you are a professional diver or a...mermaid...there is no sturdier or more waterproof watch than the Sea-Dweller. Rolex created this robust submersible model especially to withstand decompression at depths up to 4,000 feet (1,220 metres)--hence the name. (Although as a European brand, shouldn't they call the watch the Sea-Dweller 1220?)

Why is the decompression feature important, you ask? Deep-sea divers use a mix of helium and oxygen in their air tanks that can diffuse through the watch's crystal, build up pressure inside the watch, and possibly force the crystal out of the watch. When you are that deep under the water's surface, that's the last thing you want to have happen to something you've spent thousands on.

Since I prefer simple rather than overly dressy watches, especially for sports models, I really like the clean, unfussy design of the Sea-Dweller 4000. A black dial and a black rotatable bezel offset the white hands, and hour and bezel markings. A chunky stainless steel Oyster bracelet has interchangeable extension links and a tool-set. It is, clearly, a very functional watch, rather than merely a piece of wrist candy.

If you prefer a more ornamental watch, you can find superb models in Rolex's Datejust, Day-Date, or Cellini lines.

The Sea-Dweller's less submersible brother, the Submariner, might also be a good choice if you just dabble in diving as a hobby and will not go deeper than 1,000 feet (330 metres). If you like the simple elegance and functionality of both these models but don't really need an amphibious watch, then check out another Rolex watch, the Explorer II.

All three sports models have the same basic, uncluttered look: a 40 mm dial, rotatable bezel, simple markings, and chunky, robust stainless-steel Oyster wristbands.

Look at it this way: with a Rolex Sea-Dweller 4000 around your wrist, you will never swim in uncharted waters.