The MoMAR (monitoring the Mid-Atlantic Ridge) project was initiated in 1998 by the InterRidge programme to promote and coordinate long-term multidisciplinary monitoring of hydrothermal vents at the Mid-Atlantic Ridge (MAR). The major objective of the project is to study vent ecosystem dynamics using a multidisciplinary approach from geophysics to microbiology over a period of a few decades. MoMAR-D is a demonstration project of MoMAR, partially funded by the European network of excellence ESONET (http://www.esonet-noe.org/). MoMAR-D aims to deploy and manage a multidisciplinary observing system at the Lucky Strike vent field for 1 year. This large hydrothermal field is located at the centre of one of the most volcanically active segments of the MAR. The project has been set up to monitor this region to capture evidence of volcanic events, observe interactions between faulting, magmatism, and hydrothermal circulations, and to evaluate the potential impacts of these environmental factors on the unusual communities colonizing hydrothermal vents. The MoMAR-D infrastructure consists of two sea monitoring nodes (SEAMON) acoustically linked to a surface buoy with satellite communication to a land-based station. The first node will be mainly dedicated to geophysical studies, whereas the second will focus on ecological studies and chemical fluxes. The infrastructure should have been deployed in September 2010 during the MoMARSAT cruise.