This tender comprises the delivery and installation of a floating barrier for protecting the naval harbor in Den Helder, the Netherlands, preventing the entry of unwanted vessels. The barrier should stop all types of vessels, regardless the propulsion. The barrier will be permanent in nature, but it must be possible to open and close the barrier in an easy and safe way, for passing naval and other ships. The total length of the barrier is approx. 1 200 meters. The barrier has to be environmentally friendly and as silent as possible, above as well as under water. The installation of the barrier, using existing infrastructures, is part of the scope of supply. In the award phase a site visit will be possible, to view the location where the barrier is to be installed.