When you tell people that you go diving in the Swiss lakes, you can immediatly see that they consider you crazy. Many non-divers and warm water enthusiasts ask why one would torture himself with the cold temperatures to — so they think — see nothing (provided of course the water is not completely cloudy). The truth is: Yes, it is cold, yes, the marine life is less shiny than in the the Red Sea or the coral triangle and yes, it is darker.
But for many if not most people diving in Switzerland or any country offering similar conditions, the main reason they do it is for the feeling of quietness and weightlessness they get under water.
Like eating a good meal starts by looking at what is in your plate, the diving experience starts by contemplating the beautiful scenery surrounding you while you are preparing your equipment. Once you put your head under water and leave the sounds of civilisation behind you, more often than not you will end up on the edge of a chasm, contemplating the abysses. After giving in to their call you will find yourself hovering along a big wall that falls deeper than you should ever think of going without proper training. Provided the visibility is good, you will have the feeling that you are flying. Some walls are complety unstructured, a big slide into the depths. But usually you will enjoy exploring niches and passing underneath overhangs, all the while trying to find a fisch hidden in a crevice. Where there is no edge to dive into the abysses, you will be slaloming between big blocks.
It depends on the time of the year (winter usually being much better), varies from lake to lake, and even from day to day. It can go from barely seeing your hand at the end of your stretched arm, to 10 m or more. Luckily, you can find a very useful table online where people report the visibility (focuses primarily on the Swiss German part of Switzerland). Note that these data are subjective, but it works well enough. This table usually is up-to-date since the diving community is quite active. Whenever available, you will find a visibility chart on the page of every dive site described on this website.
If you are only interested in brigthly coloured species or an explosion of life like you saw in a documentary on the Great Barrier Reef, diving in Swiss waters probably is not for you. No sharks either. However, depending on the season, the location, and whether you are prepaired to take a closer look at smaller things, you will always find a fish, a snail, a worm, a crustacean or an amphibians that will catch your attention. And above the surface, water birds are always a nice distraction.
It depends on where you are living. But usually you can reach many dive sites in an hour or less. A car is indispensable though.
At approximately 20 m and deeper, the water temperatur remains constant at 5-6°C. At shallower depth, the temperature profile varies with the seasons, with surface temperatures reaching 20°C and above in summer. Note that there usually is a thermocline, the depth of which varies during the year. In winter, all lakes are at 5-6°C. Many people always dive in a dry suit, while some (some say crazy) people dive in a 7 mm wetsuit doubled by a 5 mm shorty in summer.
Temperatures on the surface are strongly under the influence of the weather conditions, and this logically is where the strongest seasonal variations are observed. The biggest differences between lakes are in the first layers below the surface. Depending on altitude, wind exposure, in- and outflows, depth and topography of the lake basin, very different conditions can predominate; compare for instance Lake Zurich and Lake Walen. The deeper you get, the more constant and even are the seasonal variations.
What is very similar between bigger lakes are the two stagnant phases in summer and winter (especially in summer), where the temperatures on the surface are clearly different from the ones in the depth, and the two circulation phases in autumn and spring, when the water circulates and shows similar temperatures throughout the depth range. The markedness and duration of these phases can however vary between lakes and years.
As mentioned above, most of the nice dives happen along big walls where if you do not pay attention you will easily sink at 50 m or deeper. Therefore, you should have a very good control over your buoyancy. Furthermore, the ground is usually composed of silt. Although it is not as vitally important as in cave diving, you should also avoid stirring it as much as possible, for the sake of the organsisms living there and the divers following you.