The problem with OLED displays is that they have a limited lifespan, as the organic elements degrade over time.
Finnish sports instrument maker Suunto has waited until there was a better alternative – Thin Film Transistor liquid crystal display (TFT LCD).
It has recently launched its flagship dive computer incorporating this new display technology, in the form of the Eon Steel. I took one with me to dive on a week’s wreck safari.

The Hardware
The Eon Steel is built with a resin polymer body with a brushed stainless-steel face housing its TFT display. The display is bonded to tough Xensation glass; the bonding process means that there is no air gap, which allows Suunto’s Brightsee colour screen to be viewed from greater angles.
The computer is powered by a rechargeable lithium-ion battery delivering 20-40 hours of dive-time from a single charge. The Eon is charged via a USB cable from a PC or Mac or from an optional mains adaptor available at extra cost.
Three push-buttons give access to the Eon’s intuitive menus and switch between screens.
A rubber protection boot is supplied along with a rubber composite strap and alternative bungee mounting kit as standard. The whole unit measures 105 x 60 x 23mm, weighs 345g and is guaranteed to a depth of 150m.

The Software
The Eon uses the established Suunto fused RGBM algorithm to maximise dive-time (the same algorithm used on Suunto’s DX mixed-gas computer).
There are at present four underwater modes: Gauge, Air, Nitrox and Trimix. A fixed-point CCR mode will be available free as a download in early 2015.
The software is Internet-upgradable through Suunto’s own DM5 program, which is also used to customise displays, plan dives and download logs. Information is displayed as a visually intuitive presentation with current depth, maximum depth, no-deco times, ambient temperature, ascent rate, gas mix and, with the addition of tank-pod transmitters, cylinder pressures.
A digital compass with 45° tilt compensation can be incorporated into the display.
The screens can be customised using the DM5 software via the data transfer / charging cable. Up to four custom displays are available for each dive mode in a choice of graphical or classic visual styles.
In Nitrox or Trimix mode, up to eight gas mixes can be pre-programmed with O2 from
5-99% and helium from 0-95%.
Each dive is sampled at 10-second intervals and recorded in the computer’s logbook, in which up to 200 hours can be stored along with a lifetime of dive history.
The computer’s parameters can be adjusted to the user’s personal preference for more conservative or aggressive profiles.

Under Water
My first impression was that this is one hefty instrument. It weighs in at a little over three-quarters of a pound, and when strapped to my wrist I was grateful for the strap-keeper on my wetsuit, which stopped the unit slipping around and ending up on the back of my hand.
As a photographer I don’t really take my eyes too far from the viewfinder, and found that the Eon sat perfectly on my strobe’s float arm, making it easier to view. So, after the first few dives, that is where it remained.
The display was very bright and easy to see from quite acute angles, even in the strong ambient light found at shallow depths in Egypt.
The information was easily disseminated, because I had customised the displays for my own needs. I preferred the graphical version, which gave a countdown icon in the form of a diminishing circle for no-stop time, deep and safety stops.
Numbers are also displayed as they count down, and these include seconds, which I found very useful.
The three buttons were easy to locate and use. They operate using the well-established short-push / long-push method, with the top and bottom buttons being used to scroll through menus accessed by the middle button.
Battery life is indicated in hours remaining. After the initial full charge, 22 hours were shown. This was enough for a full week’s liveaboard diving, although I did sit out a few dives because of blocked sinuses.
Charging was an easy affair, and with the Eon connected to my laptop it took just short of five hours to fully charge from a nearly depleted battery.
The compass is accessed with a short push of the centre button, and shows as a circle with an arrow through the centre pointing north.
Degrees are displayed in numbers in the centre of the circle. It made it easy to use while navigating to and from shotlines and between points of interest.

Suunto has poured more than 50 years’ worth of expertise into the Eon Steel and it shows.
The result is an instrument that is functional, making use of the latest in backlit colour-display technology backed up with a proven algorithm in a package that’s big, bold, bright and heavy – and that’s exactly the way I like my dive computers to be.
On the negative side, I do think that a computer of this class should be supplied with a mains charging adaptor. An extra £20 is a bit cheeky, to say the least.
If you’re thinking of wrist-mounting the Eon, my advice would be to get an exposure suit with strap-keepers, to stop the heavy lump on your wrist moving around and help to keep it secure from loss.
The longevity of TFT lighting along with upgradeable software will mean that this is an instrument that if looked after could conceivably last a lifetime, growing with your ability and diving needs.
Kudos to those clever Finns – their Eon Steel looks set to be a winner.

PRICE £795. Optional mains charger £20
MODES Gauge, Air, Nitrox, Trimix
GASSES 8, switchable
OXYGEN 5-99%
HELIUM 0-95%
UNITS Imperial or metric (changeable)
DIVE LOG 200 hours, data transfer to PC or Mac
POWER Rechargeable li-ion
SIZE 105 x 60 x 23mm
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%