A Look into the Aquastar Benthos 500

A couple of years ago I experienced a growing interest in vintage divers, especially from the sixties and seventies. These decades saw the development of the professional diver's tool watch. Most people are familiar with the Rolex Submariner, a classic developed in the fifties and still in production today. But Rolex wasn't the only producer of quality dive watches. Another, lesser known producer was Aquastar and their Benthos 500 professional diver's watch.

The Aquastar Benthos 500. Pressure tested to depths of 500 meters, a record for a diver watch at the time. This is the variant with blue bezel and dial. Pic: WatchUSeek.

The Company

Aquastar was founded in 1962 by Frédéric Robert, an experienced Scuba diver. As the name suggests, they specialized in diver's watches. Soon they expanded their production to also include regatta watches, but all the time their main focus was the development of quality watches for the emerging Scuba diving community.

Aquastar advertisement from the late sixties, early seventies. Shows the Benthos, Seatime and Regate model ranges, the latter a watch with a regatta countdown mechanism. Pic: WatchUSeek.

Frédéric Robert did not stay for long though. In 1970 he moved to Omega and became an advisor in the development of the Seamaster models. The company survived the eighties and nineties and still produces watches today, mainly regatta watches.

The Dial

The Benthos 500 could be looked upon as Aquastar's flagship in the sixties and seventies. It was the first watch pressure tested for depths up to 500 meters, hence the "500" in the name of the model. It came in two configurations, one with black dial and black bezel and another one with blue dial and bezel. I have seen watches with a combination of blue and black, but I'm uncertain if this is original from the factory or a "put-together" done at a later time.

The Aquastar Benthos 500, two blue ones and two black ones, the known configurations of this model. Pic: WatchUSeek.

The production period for the Benthos was from 1962 to 1972, although it is hard to pinpoint the production year exactly with these watches. They used modified A. Schild 1902 and 2162 movements, and as far as I know these movements did not have serial numbers that could give us the production year.

The dial and outer rotating bezel. The watch is actually a chronograph with a orange minute counter at the center of the dial and not in a sub dial as found in most other chronograph models. Pic: WatchUSeek..

The dial is a classic diver dial, legible and heavy on the lume for enhanced readability in murky waters. It is a balanced dial with enhanced minute markers every five minutes. The broad stick hour and minute hands adds to the legibility of the watch, as does the second hand. The one thing that stands out is the fourth hand shaped like an orange arrow. This is the minute counter started with the pusher at four o'clock. The diver used the combination of the bezel ring and this minute counter to time the dives.

The case of the Benthos is a classic C-shaped divers case with a raised bezel ring. It usually came on an isofrane strap or a steel bracelet. Pic: WatchUSeek.

During the production period the Benthos was also co-branded with Tissot. These watches had the Tissot logo together with the Aquastar logo on the dial.

The co-branded Aquastar/Tissot Benthos 500. It is thought that this variation was mostly distributed in Australia. Pic: www.thewatchspotblog.com.

Seems like most of these co-branded watches was sold in Australia, since most co-branded ones are found here. If anyone has more information on this co-branding and the history behind it please let me know!

Some people say that Lemania also produced these watches with the Lemania logo on the dial. I haven't been able to confirm that, so my conclusion for the time being is that there are no such Lemanias.

I have found Benthos 1000 (later generation) with Lemania on them but not 500s. It is believed though that Lemania put the Benthos 500 watches together on behalf of Aquastar as a third party service. I find it somewhat odd that Lemania would put together watches without Lemania movements in them.

The Case and Crystal

The case is a heavy C-shaped case with the Aquastar-logo on the back. This type of case is typical for the late sixties, early seventies.

The case back with the Aquastar logo. I have a weak spot for vintage cases where the logo is integrated into the case back. Pic: WatchUSeek.

The divers in this period often had this type of case or the Brevet compressor case. Luckily for me I like both cases, although in the beginning I had problems with these C-shaped cases. But here the case is somewhat balanced out by the raised bezel ring. This makes the watch look "rounder" compared to a watch were the bezel is integrated in the case. The latter exemplified by the Aquastar Seatime in the advertisement above.

The caseback came in two different variations, one with the Aquastar logo resting on a polished surface, the other where the logo is resting on a pepple blasted surface. On the caseback you will find the reference number, 1002 just below the logo.

The two different case backs. The pebble blasted surface underneath the logo to the left, the polished one to the right. Pics: WatchUSeek.

The crystal is a 4mm thick specially designed crystal that is rare and hard to come by. Should you need a new one it is relatively expensive to have one made.

The Bezel

It it not confirmed by Aquastar themselves, but it seems like the Benthos 500 came with two different bezels apart from the blue and black color configuration. One bezel is with a silver colored inner ring and the other is without this ring.

The Bezel configurations of the Benthos 500. To the left the somewhat smaller bezel without the silver colored inner ring. To the right the one with this ring. The case appears bigger with the bezel to the left. Pics: Aquastar and WUS.

Unfortunately the bezel insert is hard to find, should you need a new one. They are pretty rare and hard to come by, but I've read somewhere that it is possible to fit a Seiko one to the watch. Not original, but a solution all the same, should the bezel be in a bad shape.

The Movement

Inside the Benthos is the AS 2162 or 1902/8 movement, modified to support a center minute counter (the orange hand). AS stands for Adolph Schild, the producer of the movement. Schild produced and supplied many watch manufacturers with movements throughout the 20th century. Adolph Schild was the brother of Urs Schild, the founder of the movement production company later named Eterna (ETA).

The AS 2162 automatic movement. This was a standard movement widely used by Swiss watch manufacturers in the sixties. The one in the Benthos was modified to accommodate a center minute counter. Pic: Thewatchspot.co.uk.

The company died together with so many others during the quartz revolution, and had to close in 1983. The way I see it, the part situation is ok. I have a Glycine Airman Special with an AS 1701 inside, and both times I've had it to service, parts did not represent a problem, despite the closing of the factory way back in 1983. I guess it is on account of the wide distribution of these movements especially in the sixties. There are probably plenty of parts around still.

Caveat Emptor

If you are considering investing in an Aquastar Benthos 500, there are a few things to consider. Given that the watch in question checks out with regard to originality, some of the parts are hard to get by in the second hand market:

• If the crystal is scratched and damaged, the wait for a used (or New Old Stock) one could be long. There is a possibility to have the crystal made, but the cost is relatively high.
• If the bezel insert is damaged there could be a problem getting a nice used one. An option is to use a Seiko bezel insert, but then you technically would have a frankenwatch.

Many of these watches were used by divers and as such the conditions vary. The ones in original near-mint condition do not show up often, and when they do they are relatively expensive. One option is to go for a restored one. 

Professional restorers can effectively set the watch back to "like new" condition. But it is important to use someone who understand what an "original" restoration means. International Watch Works have experience restoring Aquastar Benthos 500s, and would know how to proceed to get the best possible result. Aquastar themselves do not restore or service old pre-quartz models as far as I know.

There is a weakness with regard to the modified minute counter. A service usually fixes this. As such, it is important to buy a watch that has been serviced, alternatively take service costs into account when agreeing on a price.

So, to sum it up, it is important to check the crystal and bezel with regard to condition. Also check if the watch has been serviced and returned with a working minute counter. The crystal should be without major cracks that cannot be buffed out. The bezel should be in an agreeable condition as well, possibly check for originality of the insert. It could be a Seiko.