In the framework of the construction of a highway in Mauritius, a large scale geophysical survey has been performed by our team. The objective was to detect local anomalies (voids, lava tubes, layer separation) down to a depth of 10 m, prior to any construction work. For this, we have conducted 24 km of seismic measurements, based on active Multichannel Analysis of Surface Waves (MASW). Due to difficult field and bad weather conditions, this 6 weeks mission has been conducted using some specifically-designed equipment, constructed by our R&D team. This includes a lightweight and robust 24 channels streamer and a mobile data acquisition unit for working in areas with limited accessibility.