Cycling is a big recreational activity all around Lake Constance. Anywhere on the shore of this lake (I used to come to the German part several times a year) you see a steady stream of cyclists of all ages going by.
You can cycle all around the lake, 250 kilometers, it you want to (I haven't done this yet), and since it is right on the shore it is pretty much flat, although this is otherwise a quite mountainous area.
There are numerous places to rent bicycles in the Austrian, Swiss and German towns all around Lake Constance.
This particular one is by the lakefront in Bregenz, at the foot of Rathausstrasse, not far from the harbor.
Sailing is another very big recreational activity on Lake Constance.
I must be one of the few people who has never sailed here (well, I used to borrow a rowboat sometimes), but one of my sons has done it a lot and even has a "Bodensee Schifferpatent", which is sort of like a driver's license for sailing and boating on the lake.
A BEAUTIFUL AND DIVIDER BETWEEN AUSTRIA AND GERMANY IS LAKE CONSTANCE.
A PLACE TO SOAK YOUR FEET AND DO A LITTLE SWIMMING AND/ OR BOATING...MAYBE A GOOD WAY TO SEE GERMANY... ALSO THERE IS A PLEASANT PARK TO WALK AND/OR JOG AND TO RELAX!!!!!
All Water Sports are very common here such as boating, Canoeing, Sailing, Swimming, Beach Volley Ball (In Summer), etc. etc.