Checkout this ambitious project to interactively map every single UWR club in the world!
At the moment I think you have to message Hannes and ask him to add your club details. There is a function for adding clubs yourself, but you may have to have a registered account with the uwr1.de website first.
Let's hope soon other clubs will be able to embed this awesome map on their websites as well.
In the meantime, the Danish website World of UW-Rugby (run by Søren Neubert, who also happens to be the President of the UWR Commission of CMAS) still has what is probably the most comprehensive list of clubs and contact details on the interwebs. However, the web design is a bit... vintage... and isn't as versatile and 'Web 2.0' as the Germans' new engineering feat.
Here is another example of German engineering made sexy.