The double-tube snorkel of the BONITO e.V.
By Dr. L. Seveke

In the 1960s, a somewhat strange-looking swimming device haunted the "diving circles" of the Potsdam district of the GDR - the BONITO snorkel, ridiculed and admired.
Laughed at, because as a "real" fin swimmer you naturally didn't need to use such "deer antlers" to perform, and admired, because you didn't know exactly what trick was behind it and also because it came from the mysterious BONITO e.V.. 
This was a club led by biologist Wolfgang M. Richter, who was not in the GST (very strange!) and did his own thing in the Baltic Sea and later in Mecklenburg lakes diving and doing independent scientific work on bodies of water.
But one thing they had in common with us normalos was that they had even less equipment than we did, which we could at least use a bit from the GST. 
So they also built their own, creatively and successfully. The double snorkel was part of it, but also rebreathers and compressed air diving equipment and cameras. They even managed to have some of the devices produced in small series under GDR conditions, the Tauchtax camera by the Curow company in Dresden (merged into VEB Pentacon in 1970) and the snorkel by VEB Degufa Berlin.
However, W. M. Richter recently told me that the production of the snorkel was not theirs at all.
So this double snorkel came into circulation in some numbers, but today it is a very rare collector's item.
The design was primarily intended to prevent pendulum breathing, which could already lead to headaches during longer working periods due to the thin PVC tubes that were only available. With the help of two flutter valves in the mouthpiece, one tube was used for inhalation and the other for exhalation.
Also for stability and wearability, the two tubes were joined over the head, where the air exited through a watertight tennis ball valve.

Picture: 1959 W.M. Richter (BONITO), filming in the Scharteisen

BONITO apparently used the double snorkel for years because it was just right for their scientific work. 
It did not catch on in the general public. Then, a few years later, there was enough thick PVC pipe for snorkels so that pendulum breathing was less of an issue. 

It was too bulky for the widespread competitive fin swimming, so we preferred the elegant middle snorkel. 

For me, the double snorkel remains an interesting symbol of self-building equipment, meticulously built to suit one's needs and breaking new ground in the process.
As an example of the work of BONITO e.V.: Biologische Station Feldberg t1p.de/lpyt 

When I strolled across the BOOT a few years ago, I suddenly believed in a déjà vue. The double snorkel was back!
Of course, it was praised as a completely new invention with exhilarating advantages that had never been seen before ;-).
Admittedly, it didn't have that much in common with the good old BONITO. Design and manufacturing technology differed anyway, but the aim of use was also different. 
Pendulum breathing is avoided by the exhalation valve located directly in front of the mouth, as is already common with today's monotube snorkels. 

And today's divers are used to the bubbling with bubbles in front of their faces from their single-tube machines.
But the cross-section of the inhalation tube is practically doubled, which reduces breathing resistance. And since we all do high-performance sports nowadays, this is absolutely necessary, like the carbon bicycle for the pensioner.
The symmetrical design, however, improves the wearing characteristics; there should be no fluttering as with the baggy attachment of the monotube snorkel to the mask strap.
High-tech snorkel masks are now also equipped with double snorkels. With them, you're sure to be top dog at the pool.
Let's see what happens next.

A few more nice pictures from the activities of 
BONITO e. V., thanks to W. M. Richter for the release:

Picture: 1959, at the amber island in front of Darßer Ort.
Picture: 1955, Henning Sich off the west coast of Darß, diving taxi photo
Picture: 1964, Richter & Dembinsky in dry diving suits