Diver watches differ from regular watches in 5 ways:

They are water resistant to at least 100M (professional dive watches need to be 200M). They have a rotating bezel that can only be turned counterclockwise so you can keep track of your dive time. They have a screw-down crown and caseback to prevent water from getting into the watch. They have highly visible luminescent markers so you can see the time in the dark. They are certified to the ISO 6425 standards, which means the watch has passed all the tests required to be certified as a dive watch.

A diver watch is not just different from an ordinary watch in water resistance; there is much more to it. A professional dive watch is designed to withstand a special set of circumstances that would destroy an ordinary timepiece in minutes - intense pressure, complete darkness, cold temperatures and the ability to measure elapsed time to the second with a glance. Part of the appeal of dive watches as everyday watches for people who never go in water deeper than a swimming pool is understanding what makes a dive watch really different.

The ISO Standard: What Professional Dive Watches Must Pass

The international standard for divers' watches is ISO 6425, the defining document for professional dive watches. A watch that conforms to this standard must pass a series of tests far beyond the basic water resistance rating.

Recreational diving certification requires at least 100M water resistance (ISO 6425), and most professional dive watches are rated to 200M or more. The watch must keep within certain tolerances of accuracy under pressure. Lume must be visible in total darkness. The bezel needs to be functional when underwater. And the case must pass the tests of condensation, magnetic field, and shock resistance.

The Watch Connection has the complete range of Seiko Prospex divers from the Automatic Diver SRPE93 to the Heritage SPB297, all built to ISO standards for scuba diving at 200M. That certification is not a marketing claim; it's a documented test result that separates professional dive watches from water-resistant fashion watches rated to 30M or 50M that aren't safe to intentionally submerge.

The Unidirectional Rotating Bezel

It is this feature that visually distinguishes a diver watch from other families of watches. The unidirectional rotating bezel can only be turned anticlockwise - never clockwise. When the dive starts, the diver rotates the bezel until the zero mark is opposite the minute hand. As the dive progresses, the minute hand moves and the elapsed time is read off against the bezel scale.

This is a safety feature for one-direction rotation. If you accidentally bump the bezel while diving, the only way you can turn it is towards more elapsed time - never less. If the bezel is rotated clockwise, the dive elapsed time could be underestimated, and this could directly impact the safety of decompression.

The Seiko Prospex Automatic Diver SRPE93 is just that arrangement. A black unidirectional rotating elapsed timing bezel, matched with a clean black dial for easy visibility underwater. The Seiko Prospex SPB317 takes this one step further with super-hard coating on the stainless steel case, and a curved sapphire crystal with anti-reflective coating on the inside surface, to handle both scratch resistance and glare in underwater conditions.

Screw-Down Crown and Caseback

The crown on a regular watch pushes into the case and depends solely on gaskets to keep water out. Under duress, this is not enough. Professional dive watches use a screw-down crown that threads into the case, compressing the gasket against a metal-to-metal seal that holds integrity at diving depths.

The Seiko Prospex Solar Diver SNE573 and the Automatic Diver SRPE93 both have screw-down crowns and casebacks, two independent seals that both need to be engaged for the watch to maintain its rated water resistance. Most divers soon develop the habit of checking that the crown is screwed down tight before any contact with water.

Luminescence: Reading Time in Darkness

Automatic dive watches and professional dive watches use high-grade luminescent compounds on their hands and indices that absorb ambient light and emit it for hours afterwards. All the watches in the Prospex collection feature Seiko's proprietary LumiBrite compound (SRPE93, SPB297, SPB317 and the 1965 Re-Creation Limited Edition SJE093).

There is a legibility requirement in ISO 6425. The lume must be readable in total darkness at a distance of 25cm. A normal fashion watch with printed or thinly laid lume will fail this test in a matter of hours.

Automatic Dive Watches vs Solar Dive Watches

The Watch Connection's Prospex line offers examples of both approaches to the movement in professional dive watches.

Both the SRPE93 and SPB317 diving watches are automatic, with a 24-jewel automatic movement beating at a frequency of 21,600 vibrations per hour with a power reserve of 41 hours. The movement is wound by motion of the wrist; no battery needed. This is practical and self-sustaining for divers wearing their watch every day.

Watches such as the solar-powered SNE573 work differently. Any light source will charge a rechargeable cell via a solar cell, giving you a power reserve of 10 months after a full charge. No battery changes, no winding, the watch just keeps on going as long as it gets some light once in a while. The Seiko Prospex Solar Analogue-Digital SNJ039 takes this even further with a 6-month power reserve and a full digital display for chronograph, dual time, alarm and date functions, in addition to the analogue dive display.

Both are automatic watches, so neither needs to be wound or have the battery changed. It's not the difference in diving capability; it's the experience of how you generate the energy of movement. Both are ISO 200M standards.

Diver Watches as Everyday Watches

The truth is, for non-divers, automatic dive watches are one of the most popular categories of watch to wear on a daily basis, and with good reason. They are far more durable, more legible, and more ruggedly built than most dress or everyday watches at similar price points.

A watch rated to 200M with a screw-down crown handles hand-washing, rain, beach trips, and pool sessions without any thought. The high contrast dial with strong lume is easy to read in any light condition. The case construction withstands daily wear in a way that thinner dress watches cannot match.

This two-pronged appeal is exemplified by the Seiko Prospex 1965 Heritage Save the Ocean SPB297, a modern reinterpretation of Seiko's original diver's watch of 1965, Japan's first. It's certified for serious diving use, and built with the case depth and materials that come with that. It is also a very unique everyday watch with history behind it that makes it worth wearing whether the closest ocean is 10 minutes or 10 hours away.

The Oris Aquis Date: Swiss Professional Dive Watches

The Watch Connection also has the Oris Aquis Date as a Swiss professional dive watch option, in addition to Seiko. Oris is one of the last independent Swiss watchmakers, and the Aquis was designed from the outset as a serious tool watch. The Watch Connection carries the Aquis, a luxury automatic dive watch with a unidirectional bezel, sapphire crystal, Swiss automatic movement,t and case built to resist water to 300M.

Why Buy from The Watch Connection

Based in a 3,000 square foot showroom in Orange County, California, The Watch Connection offers one of the largest selections of Seiko Prospex diver watches from one authorised retailer. Within the Prospex line of the store, there are automatic and solar movement references, standard and limited edition references, with prices from accessible to collector-grade.

Pre-owned dive watches are professionally authenticated before arriving on the floor, which matters for buyers who are considering references like the SJE093 1965 Re-Creation limited edition, where the serial number and condition of the original seals are significant. The team's broad knowledge of dive watch specs, ISO ratings, movement calibres, lume compounds and bezel function makes navigating the category in the flesh a lot easier than online.

Visit thewatchconnection.com for the complete collection of diver watches or come to our showroom in Orange County and compare automatic and solar dive watches side by side.