This article describes a novel voltammetric in-situ profiling system (VIP System) for continuous, real-time monitoring of trace elements in fresh and seawater down to 500 meter depth. The VIP System has been designed using advanced microprocessor and telemetry technology. The heart of the submersible voltammetric probe is a Hg-plated Ir-based microsensor covered with an antifouling gel membrane. This gel integrated microsensor allows direct voltammetric measurements of trace metals in complex media without physical and chemical interferences of the test solution. A detailed description of the system is given and examples of environmental applications are reported for in-situ trace metal monitoring in oxygen saturated seawater as well as for in-situ profiling of MnII in anoxic lake water. The results indicate that the VIP System is robust and reliable and that in-situ measurements of mobile fraction of trace metals can be achieved down to very low concentration levels (ca. 5 ppt).