Hellevoetsluis is a town located in the western region of the Netherlands. It is situated within the municipality of Voorne-Putten in the province of South Holland.
The area formerly functioned as an independent municipality covering 61.20 km² (23.63 sq mi), with approximately 20.10 km² (7.76 sq mi) consisting of water. The former municipal boundaries included the population centers of Nieuw-Helvoet, Nieuwenhoorn, and Oude en Nieuwe Struiten.