People & Vessels. These are the driving forces behind the success of the Jan De Nul Group. Thanks to its skilled employees and ultramodern, constantly growing fleet, today the group ranks at the top of the international dredging and marine related industry. Also with regard to civil engineering, Jan De Nul is one of the largest contractors in Belgium. The company also has a separate environmental subsidiary: Envisan. Thanks to these three pillars, there is a constant growth, both national and international.